Primitive Type i8

1.0.0

Expand description

The 8-bit signed integer type.

Implementations§

Source §

assert_eq!(i8::MAX.count_zeros(), 1);

1.0.0 (const: 1.32.0) · Source

pub const fn leading_zeros(self) -> u32

Returns the number of leading zeros in the binary representation of self.

Depending on what you’re doing with the value, you might also be interested in the ilog2 function which returns a consistent number, even if the type widens.

§Examples

let n = -1i8;

assert_eq!(n.leading_zeros(), 0);

1.0.0 (const: 1.32.0) · Source

pub const fn trailing_zeros(self) -> u32

Returns the number of trailing zeros in the binary representation of self.

§Examples

let n = -4i8;

assert_eq!(n.trailing_zeros(), 2);

1.46.0 (const: 1.46.0) · Source

pub const fn leading_ones(self) -> u32

Returns the number of leading ones in the binary representation of self.

§Examples

let n = -1i8;

assert_eq!(n.leading_ones(), 8);

1.46.0 (const: 1.46.0) · Source

pub const fn trailing_ones(self) -> u32

Returns the number of trailing ones in the binary representation of self.

§Examples

let n = 3i8;

assert_eq!(n.trailing_ones(), 2);

1.97.0 (const: 1.97.0) · Source

pub const fn isolate_highest_one(self) -> Self

Returns self with only the most significant bit set, or 0 if the input is 0.

§Examples

let n: i8 = 0b_01100100;

assert_eq!(n.isolate_highest_one(), 0b_01000000);
assert_eq!(0_i8.isolate_highest_one(), 0);

1.97.0 (const: 1.97.0) · Source

pub const fn isolate_lowest_one(self) -> Self

Returns self with only the least significant bit set, or 0 if the input is 0.

§Examples

let n: i8 = 0b_01100100;

assert_eq!(n.isolate_lowest_one(), 0b_00000100);
assert_eq!(0_i8.isolate_lowest_one(), 0);

1.97.0 (const: 1.97.0) · Source

pub const fn highest_one(self) -> Option<u32>

Returns the index of the highest bit set to one in self, or None if self is 0.

Note that for non-negative numbers, this is equivalent to checked_ilog2.

§Examples

assert_eq!(0b0_i8.highest_one(), None);
assert_eq!(0b1_i8.highest_one(), Some(0));
assert_eq!(0b1_0000_i8.highest_one(), Some(4));
assert_eq!(0b1_1111_i8.highest_one(), Some(4));

1.97.0 (const: 1.97.0) · Source

pub const fn lowest_one(self) -> Option<u32>

Returns the index of the lowest bit set to one in self, or None if self is 0.

§Examples

assert_eq!(0b0_i8.lowest_one(), None);
assert_eq!(0b1_i8.lowest_one(), Some(0));
assert_eq!(0b1_0000_i8.lowest_one(), Some(4));
assert_eq!(0b1_1111_i8.lowest_one(), Some(0));

1.87.0 (const: 1.87.0) · Source

pub const fn cast_unsigned(self) -> u8

Returns the bit pattern of self reinterpreted as an unsigned integer of the same size.

This produces the same result as an as cast, but ensures that the bit-width remains the same.

§Examples

let n = -1i8;

assert_eq!(n.cast_unsigned(), u8::MAX);

Source

pub const fn saturating_cast_unsigned(self) -> u8

🔬This is a nightly-only experimental API. (integer_cast_extras #154650)

Saturating conversion of self to an unsigned integer of the same size.

Negative values are clamped to 0.

For other kinds of unsigned integer casts, see cast_unsigned, checked_cast_unsigned, or strict_cast_unsigned.

§Examples

#![feature(integer_cast_extras)]
let n = i8::MIN;

assert_eq!(n.saturating_cast_unsigned(), 0u8);
assert_eq!(64i8.saturating_cast_unsigned(), 64u8);

Source

pub const fn checked_cast_unsigned(self) -> Option<u8>

🔬This is a nightly-only experimental API. (integer_cast_extras #154650)

Checked conversion of self to an unsigned integer of the same size, returning None if self is negative.

For other kinds of unsigned integer casts, see cast_unsigned, saturating_cast_unsigned, or strict_cast_unsigned.

§Examples

#![feature(integer_cast_extras)]
let n = i8::MIN;

assert_eq!(n.checked_cast_unsigned(), None);
assert_eq!(64i8.checked_cast_unsigned(), Some(64u8));

Source

pub const fn strict_cast_unsigned(self) -> u8

🔬This is a nightly-only experimental API. (integer_cast_extras #154650)

Strict conversion of self to an unsigned integer of the same size, which panics if self is negative.

For other kinds of unsigned integer casts, see cast_unsigned, checked_cast_unsigned, or saturating_cast_unsigned.

§Examples

#![feature(integer_cast_extras)]
let _ = i8::MIN.strict_cast_unsigned();

1.0.0 (const: 1.32.0) · Source

pub const fn rotate_left(self, n: u32) -> Self

Shifts the bits to the left by a specified amount, n, wrapping the truncated bits to the end of the resulting integer.

rotate_left(n) is equivalent to applying rotate_left(1) a total of n times. In particular, a rotation by the number of bits in self returns the input value unchanged.

Please note this isn’t the same operation as the << shifting operator!

§Examples

let n = -0x7ei8;
let m = 0xa;

assert_eq!(n.rotate_left(2), m);
assert_eq!(n.rotate_left(1024), n);

1.0.0 (const: 1.32.0) · Source

pub const fn rotate_right(self, n: u32) -> Self

Shifts the bits to the right by a specified amount, n, wrapping the truncated bits to the beginning of the resulting integer.

rotate_right(n) is equivalent to applying rotate_right(1) a total of n times. In particular, a rotation by the number of bits in self returns the input value unchanged.

Please note this isn’t the same operation as the >> shifting operator!

§Examples

let n = 0xai8;
let m = -0x7e;

assert_eq!(n.rotate_right(2), m);
assert_eq!(n.rotate_right(1024), n);

1.0.0 (const: 1.32.0) · Source

pub const fn swap_bytes(self) -> Self

Reverses the byte order of the integer.

§Examples

let n = 0x12i8;

let m = n.swap_bytes();

assert_eq!(m, 0x12);

1.37.0 (const: 1.37.0) · Source

pub const fn reverse_bits(self) -> Self

Reverses the order of bits in the integer. The least significant bit becomes the most significant bit, second least-significant bit becomes second most-significant bit, etc.

§Examples

let n = 0x12i8;
let m = n.reverse_bits();

assert_eq!(m, 0x48);
assert_eq!(0, 0i8.reverse_bits());

1.0.0 (const: 1.32.0) · Source

pub const fn from_be(x: Self) -> Self

Converts an integer from big endian to the target’s endianness.

On big endian this is a no-op. On little endian the bytes are swapped.

§Examples

let n = 0x1Ai8;

if cfg!(target_endian = "big") {
    assert_eq!(i8::from_be(n), n)
} else {
    assert_eq!(i8::from_be(n), n.swap_bytes())
}

1.0.0 (const: 1.32.0) · Source

pub const fn from_le(x: Self) -> Self

Converts an integer from little endian to the target’s endianness.

On little endian this is a no-op. On big endian the bytes are swapped.

§Examples

let n = 0x1Ai8;

if cfg!(target_endian = "little") {
    assert_eq!(i8::from_le(n), n)
} else {
    assert_eq!(i8::from_le(n), n.swap_bytes())
}

1.0.0 (const: 1.32.0) · Source

pub const fn to_be(self) -> Self

Swaps bytes of self on little endian targets.

On big endian this is a no-op.

The returned value has the same type as self, and will be interpreted as (a potentially different) value of a native-endian i8.

See to_be_bytes() for a type-safe alternative.

§Examples

let n = 0x1Ai8;

if cfg!(target_endian = "big") {
    assert_eq!(n.to_be(), n)
} else {
    assert_eq!(n.to_be(), n.swap_bytes())
}

1.0.0 (const: 1.32.0) · Source

pub const fn to_le(self) -> Self

Swaps bytes of self on big endian targets.

On little endian this is a no-op.

The returned value has the same type as self, and will be interpreted as (a potentially different) value of a native-endian i8.

See to_le_bytes() for a type-safe alternative.

§Examples

let n = 0x1Ai8;

if cfg!(target_endian = "little") {
    assert_eq!(n.to_le(), n)
} else {
    assert_eq!(n.to_le(), n.swap_bytes())
}

1.0.0 (const: 1.47.0) · Source

pub const fn checked_add(self, rhs: Self) -> Option<Self>

Checked integer addition. Computes self + rhs, returning None if overflow occurred.

§Examples

assert_eq!((i8::MAX - 2).checked_add(1), Some(i8::MAX - 1));
assert_eq!((i8::MAX - 2).checked_add(3), None);

1.91.0 (const: 1.91.0) · Source

pub const fn strict_add(self, rhs: Self) -> Self

Strict integer addition. Computes self + rhs, panicking if overflow occurred.

§Panics

§Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

§Examples

assert_eq!((i8::MAX - 2).strict_add(1), i8::MAX - 1);

The following panics because of overflow:

let _ = (i8::MAX - 2).strict_add(3);

1.79.0 (const: 1.79.0) · Source

pub const unsafe fn unchecked_add(self, rhs: Self) -> Self

Unchecked integer addition. Computes self + rhs, assuming overflow cannot occur.

Calling x.unchecked_add(y) is semantically equivalent to calling x.checked_add(y).unwrap_unchecked().

If you’re just trying to avoid the panic in debug mode, then do not use this. Instead, you’re looking for wrapping_add.

§Safety

This results in undefined behavior when self + rhs > i8::MAX or self + rhs < i8::MIN, i.e. when checked_add would return None.

1.66.0 (const: 1.66.0) · Source

pub const fn checked_add_unsigned(self, rhs: u8) -> Option<Self>

Checked addition with an unsigned integer. Computes self + rhs, returning None if overflow occurred.

§Examples

assert_eq!(1i8.checked_add_unsigned(2), Some(3));
assert_eq!((i8::MAX - 2).checked_add_unsigned(3), None);

1.91.0 (const: 1.91.0) · Source

pub const fn strict_add_unsigned(self, rhs: u8) -> Self

Strict addition with an unsigned integer. Computes self + rhs, panicking if overflow occurred.

§Panics

§Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

§Examples

assert_eq!(1i8.strict_add_unsigned(2), 3);

The following panics because of overflow:

let _ = (i8::MAX - 2).strict_add_unsigned(3);

1.0.0 (const: 1.47.0) · Source

pub const fn checked_sub(self, rhs: Self) -> Option<Self>

Checked integer subtraction. Computes self - rhs, returning None if overflow occurred.

§Examples

assert_eq!((i8::MIN + 2).checked_sub(1), Some(i8::MIN + 1));
assert_eq!((i8::MIN + 2).checked_sub(3), None);

1.91.0 (const: 1.91.0) · Source

pub const fn strict_sub(self, rhs: Self) -> Self

Strict integer subtraction. Computes self - rhs, panicking if overflow occurred.

§Panics

§Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

§Examples

assert_eq!((i8::MIN + 2).strict_sub(1), i8::MIN + 1);

The following panics because of overflow:

let _ = (i8::MIN + 2).strict_sub(3);

1.79.0 (const: 1.79.0) · Source

pub const unsafe fn unchecked_sub(self, rhs: Self) -> Self

Unchecked integer subtraction. Computes self - rhs, assuming overflow cannot occur.

Calling x.unchecked_sub(y) is semantically equivalent to calling x.checked_sub(y).unwrap_unchecked().

If you’re just trying to avoid the panic in debug mode, then do not use this. Instead, you’re looking for wrapping_sub.

§Safety

This results in undefined behavior when self - rhs > i8::MAX or self - rhs < i8::MIN, i.e. when checked_sub would return None.

1.66.0 (const: 1.66.0) · Source

pub const fn checked_sub_unsigned(self, rhs: u8) -> Option<Self>

Checked subtraction with an unsigned integer. Computes self - rhs, returning None if overflow occurred.

§Examples

assert_eq!(1i8.checked_sub_unsigned(2), Some(-1));
assert_eq!((i8::MIN + 2).checked_sub_unsigned(3), None);

1.91.0 (const: 1.91.0) · Source

pub const fn strict_sub_unsigned(self, rhs: u8) -> Self

Strict subtraction with an unsigned integer. Computes self - rhs, panicking if overflow occurred.

§Panics

§Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

§Examples

assert_eq!(1i8.strict_sub_unsigned(2), -1);

The following panics because of overflow:

let _ = (i8::MIN + 2).strict_sub_unsigned(3);

1.0.0 (const: 1.47.0) · Source

pub const fn checked_mul(self, rhs: Self) -> Option<Self>

Checked integer multiplication. Computes self * rhs, returning None if overflow occurred.

§Examples

assert_eq!(i8::MAX.checked_mul(1), Some(i8::MAX));
assert_eq!(i8::MAX.checked_mul(2), None);

1.91.0 (const: 1.91.0) · Source

pub const fn strict_mul(self, rhs: Self) -> Self

Strict integer multiplication. Computes self * rhs, panicking if overflow occurred.

§Panics

§Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

§Examples

assert_eq!(i8::MAX.strict_mul(1), i8::MAX);

The following panics because of overflow:

let _ = i8::MAX.strict_mul(2);

1.79.0 (const: 1.79.0) · Source

pub const unsafe fn unchecked_mul(self, rhs: Self) -> Self

Unchecked integer multiplication. Computes self * rhs, assuming overflow cannot occur.

Calling x.unchecked_mul(y) is semantically equivalent to calling x.checked_mul(y).unwrap_unchecked().

If you’re just trying to avoid the panic in debug mode, then do not use this. Instead, you’re looking for wrapping_mul.

§Safety

This results in undefined behavior when self * rhs > i8::MAX or self * rhs < i8::MIN, i.e. when checked_mul would return None.

1.0.0 (const: 1.52.0) · Source

pub const fn checked_div(self, rhs: Self) -> Option<Self>

Checked integer division. Computes self / rhs, returning None if rhs == 0 or the division results in overflow.

§Examples

assert_eq!((i8::MIN + 1).checked_div(-1), Some(127));
assert_eq!(i8::MIN.checked_div(-1), None);
assert_eq!((1i8).checked_div(0), None);

1.91.0 (const: 1.91.0) · Source

pub const fn strict_div(self, rhs: Self) -> Self

Strict integer division. Computes self / rhs, panicking if overflow occurred.

§Panics

This function will panic if rhs is zero.

§Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

The only case where such an overflow can occur is when one divides MIN / -1 on a signed type (where MIN is the negative minimal value for the type); the result of this is -MIN, a positive value that is too large to represent in the type.

Note that this is equivalent to normal division: MIN / -1 will also panic both in debug and release builds.

§Examples

assert_eq!((i8::MIN + 1).strict_div(-1), 127);

The following panics because of overflow:

let _ = i8::MIN.strict_div(-1);

The following panics because of division by zero:

let _ = (1i8).strict_div(0);

1.38.0 (const: 1.52.0) · Source

pub const fn checked_div_euclid(self, rhs: Self) -> Option<Self>

Checked Euclidean division. Computes self.div_euclid(rhs), returning None if rhs == 0 or the division results in overflow.

§Examples

assert_eq!((i8::MIN + 1).checked_div_euclid(-1), Some(127));
assert_eq!(i8::MIN.checked_div_euclid(-1), None);
assert_eq!((1i8).checked_div_euclid(0), None);

1.91.0 (const: 1.91.0) · Source

pub const fn strict_div_euclid(self, rhs: Self) -> Self

Strict Euclidean division. Computes self.div_euclid(rhs), panicking if overflow occurred.

§Panics

This function will panic if rhs is zero.

§Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

The only case where such an overflow can occur is when one divides MIN / -1 on a signed type (where MIN is the negative minimal value for the type); the result of this is -MIN, a positive value that is too large to represent in the type.

Note that this is equivalent to div_euclid: MIN.div_euclid(-1) will also panic both in debug and release builds.

§Examples

assert_eq!((i8::MIN + 1).strict_div_euclid(-1), 127);

The following panics because of overflow:

let _ = i8::MIN.strict_div_euclid(-1);

The following panics because of division by zero:

let _ = (1i8).strict_div_euclid(0);

Source

pub const fn checked_div_exact(self, rhs: Self) -> Option<Self>

🔬This is a nightly-only experimental API. (exact_div #139911)

Checked integer division without remainder. Computes self / rhs, returning None if rhs == 0, the division results in overflow, or self % rhs != 0.

§Examples

#![feature(exact_div)]
assert_eq!((i8::MIN + 1).checked_div_exact(-1), Some(127));
assert_eq!((-5i8).checked_div_exact(2), None);
assert_eq!(i8::MIN.checked_div_exact(-1), None);
assert_eq!((1i8).checked_div_exact(0), None);

Source

pub const fn div_exact(self, rhs: Self) -> Option<Self>

🔬This is a nightly-only experimental API. (exact_div #139911)

Integer division without remainder. Computes self / rhs, returning None if self % rhs != 0.

§Panics

This function will panic if rhs == 0.

§Overflow behavior

On overflow, this function will panic if overflow checks are enabled (default in debug mode) and wrap if overflow checks are disabled (default in release mode).

§Examples

#![feature(exact_div)]
assert_eq!(64i8.div_exact(2), Some(32));
assert_eq!(64i8.div_exact(32), Some(2));
assert_eq!((i8::MIN + 1).div_exact(-1), Some(127));
assert_eq!(65i8.div_exact(2), None);

#![feature(exact_div)]
let _ = 64i8.div_exact(0);

#![feature(exact_div)]
let _ = i8::MIN.div_exact(-1);

Source

pub const unsafe fn unchecked_div_exact(self, rhs: Self) -> Self

🔬This is a nightly-only experimental API. (exact_div #139911)

Unchecked integer division without remainder. Computes self / rhs.

§Safety

This results in undefined behavior when rhs == 0, self % rhs != 0, or self == i8::MIN && rhs == -1, i.e. when checked_div_exact would return None.

1.7.0 (const: 1.52.0) · Source

pub const fn checked_rem(self, rhs: Self) -> Option<Self>

Checked integer remainder. Computes self % rhs, returning None if rhs == 0 or the division results in overflow.

§Examples

assert_eq!(5i8.checked_rem(2), Some(1));
assert_eq!(5i8.checked_rem(0), None);
assert_eq!(i8::MIN.checked_rem(-1), None);

1.91.0 (const: 1.91.0) · Source

pub const fn strict_rem(self, rhs: Self) -> Self

Strict integer remainder. Computes self % rhs, panicking if the division results in overflow.

§Panics

This function will panic if rhs is zero.

§Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

The only case where such an overflow can occur is x % y for MIN / -1 on a signed type (where MIN is the negative minimal value), which is invalid due to implementation artifacts.

§Examples

assert_eq!(5i8.strict_rem(2), 1);

The following panics because of division by zero:

let _ = 5i8.strict_rem(0);

The following panics because of overflow:

let _ = i8::MIN.strict_rem(-1);

1.38.0 (const: 1.52.0) · Source

pub const fn checked_rem_euclid(self, rhs: Self) -> Option<Self>

Checked Euclidean remainder. Computes self.rem_euclid(rhs), returning None if rhs == 0 or the division results in overflow.

§Examples

assert_eq!(5i8.checked_rem_euclid(2), Some(1));
assert_eq!(5i8.checked_rem_euclid(0), None);
assert_eq!(i8::MIN.checked_rem_euclid(-1), None);

1.91.0 (const: 1.91.0) · Source

pub const fn strict_rem_euclid(self, rhs: Self) -> Self

Strict Euclidean remainder. Computes self.rem_euclid(rhs), panicking if the division results in overflow.

§Panics

This function will panic if rhs is zero.

§Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

The only case where such an overflow can occur is x % y for MIN / -1 on a signed type (where MIN is the negative minimal value), which is invalid due to implementation artifacts.

§Examples

assert_eq!(5i8.strict_rem_euclid(2), 1);

The following panics because of division by zero:

let _ = 5i8.strict_rem_euclid(0);

The following panics because of overflow:

let _ = i8::MIN.strict_rem_euclid(-1);

1.7.0 (const: 1.47.0) · Source

pub const fn checked_neg(self) -> Option<Self>

Checked negation. Computes -self, returning None if self == MIN.

§Examples

assert_eq!(5i8.checked_neg(), Some(-5));
assert_eq!(i8::MIN.checked_neg(), None);

1.93.0 (const: 1.93.0) · Source

pub const unsafe fn unchecked_neg(self) -> Self

Unchecked negation. Computes -self, assuming overflow cannot occur.

§Safety

This results in undefined behavior when self == i8::MIN, i.e. when checked_neg would return None.

1.91.0 (const: 1.91.0) · Source

pub const fn strict_neg(self) -> Self

Strict negation. Computes -self, panicking if self == MIN.

§Panics

§Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

§Examples

assert_eq!(5i8.strict_neg(), -5);

The following panics because of overflow:

let _ = i8::MIN.strict_neg();

1.7.0 (const: 1.47.0) · Source

pub const fn checked_shl(self, rhs: u32) -> Option<Self>

Checked shift left. Computes self << rhs, returning None if rhs is larger than or equal to the number of bits in self.

§Examples

assert_eq!(0x1i8.checked_shl(4), Some(0x10));
assert_eq!(0x1i8.checked_shl(129), None);
assert_eq!(0x10i8.checked_shl(7), Some(0));

1.91.0 (const: 1.91.0) · Source

pub const fn strict_shl(self, rhs: u32) -> Self

Strict shift left. Computes self << rhs, panicking if rhs is larger than or equal to the number of bits in self.

§Panics

§Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

§Examples

assert_eq!(0x1i8.strict_shl(4), 0x10);

The following panics because of overflow:

let _ = 0x1i8.strict_shl(129);

1.93.0 (const: 1.93.0) · Source

pub const unsafe fn unchecked_shl(self, rhs: u32) -> Self

Unchecked shift left. Computes self << rhs, assuming that rhs is less than the number of bits in self.

§Safety

This results in undefined behavior if rhs is larger than or equal to the number of bits in self, i.e. when checked_shl would return None.

1.87.0 (const: 1.87.0) · Source

pub const fn unbounded_shl(self, rhs: u32) -> i8

Unbounded shift left. Computes self << rhs, without bounding the value of rhs.

If rhs is larger or equal to the number of bits in self, the entire value is shifted out, and 0 is returned.

§Examples

assert_eq!(0x1_i8.unbounded_shl(4), 0x10);
assert_eq!(0x1_i8.unbounded_shl(129), 0);
assert_eq!(0b101_i8.unbounded_shl(0), 0b101);
assert_eq!(0b101_i8.unbounded_shl(1), 0b1010);
assert_eq!(0b101_i8.unbounded_shl(2), 0b10100);
assert_eq!(42_i8.unbounded_shl(8), 0);
assert_eq!(42_i8.unbounded_shl(1).unbounded_shl(7), 0);
assert_eq!((-13_i8).unbounded_shl(8), 0);
assert_eq!((-13_i8).unbounded_shl(1).unbounded_shl(7), 0);

Source

pub const fn shl_exact(self, rhs: u32) -> Option<i8>

🔬This is a nightly-only experimental API. (exact_bitshifts #144336)

Exact shift left. Computes self << rhs as long as it can be reversed losslessly.

Returns None if any bits that would be shifted out differ from the resulting sign bit or if rhs >= i8::BITS. Otherwise, returns Some(self << rhs).

§Examples

#![feature(exact_bitshifts)]

assert_eq!(0x1i8.shl_exact(4), Some(0x10));
assert_eq!(0x1i8.shl_exact(i8::BITS - 2), Some(1 << i8::BITS - 2));
assert_eq!(0x1i8.shl_exact(i8::BITS - 1), None);
assert_eq!((-0x2i8).shl_exact(i8::BITS - 2), Some(-0x2 << i8::BITS - 2));
assert_eq!((-0x2i8).shl_exact(i8::BITS - 1), None);

Source

pub const unsafe fn unchecked_shl_exact(self, rhs: u32) -> i8

🔬This is a nightly-only experimental API. (exact_bitshifts #144336)

Unchecked exact shift left. Computes self << rhs, assuming the operation can be losslessly reversed and rhs cannot be larger than i8::BITS.

§Safety

This results in undefined behavior when rhs >= self.leading_zeros() && rhs >= self.leading_ones() i.e. when i8::shl_exact would return None.

1.7.0 (const: 1.47.0) · Source

pub const fn checked_shr(self, rhs: u32) -> Option<Self>

Checked shift right. Computes self >> rhs, returning None if rhs is larger than or equal to the number of bits in self.

§Examples

assert_eq!(0x10i8.checked_shr(4), Some(0x1));
assert_eq!(0x10i8.checked_shr(128), None);

1.91.0 (const: 1.91.0) · Source

pub const fn strict_shr(self, rhs: u32) -> Self

Strict shift right. Computes self >> rhs, panicking if rhs is larger than or equal to the number of bits in self.

§Panics

§Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

§Examples

assert_eq!(0x10i8.strict_shr(4), 0x1);

The following panics because of overflow:

let _ = 0x10i8.strict_shr(128);

1.93.0 (const: 1.93.0) · Source

pub const unsafe fn unchecked_shr(self, rhs: u32) -> Self

Unchecked shift right. Computes self >> rhs, assuming that rhs is less than the number of bits in self.

§Safety

This results in undefined behavior if rhs is larger than or equal to the number of bits in self, i.e. when checked_shr would return None.

1.87.0 (const: 1.87.0) · Source

pub const fn unbounded_shr(self, rhs: u32) -> i8

Unbounded shift right. Computes self >> rhs, without bounding the value of rhs.

If rhs is larger or equal to the number of bits in self, the entire value is shifted out, which yields 0 for a positive number, and -1 for a negative number.

§Examples

assert_eq!(0x10_i8.unbounded_shr(4), 0x1);
assert_eq!(0x10_i8.unbounded_shr(129), 0);
assert_eq!(i8::MIN.unbounded_shr(129), -1);
assert_eq!(0b1010_i8.unbounded_shr(0), 0b1010);
assert_eq!(0b1010_i8.unbounded_shr(1), 0b101);
assert_eq!(0b1010_i8.unbounded_shr(2), 0b10);
assert_eq!(42_i8.unbounded_shr(8), 0);
assert_eq!(42_i8.unbounded_shr(1).unbounded_shr(7), 0);
assert_eq!((-13_i8).unbounded_shr(8), -1);
assert_eq!((-13_i8).unbounded_shr(1).unbounded_shr(7), -1);

Source

pub const fn shr_exact(self, rhs: u32) -> Option<i8>

🔬This is a nightly-only experimental API. (exact_bitshifts #144336)

Exact shift right. Computes self >> rhs as long as it can be reversed losslessly.

Returns None if any non-zero bits would be shifted out or if rhs >= i8::BITS. Otherwise, returns Some(self >> rhs).

§Examples

#![feature(exact_bitshifts)]

assert_eq!(0x10i8.shr_exact(4), Some(0x1));
assert_eq!(0x10i8.shr_exact(5), None);

Source

pub const unsafe fn unchecked_shr_exact(self, rhs: u32) -> i8

🔬This is a nightly-only experimental API. (exact_bitshifts #144336)

Unchecked exact shift right. Computes self >> rhs, assuming the operation can be losslessly reversed and rhs cannot be larger than i8::BITS.

§Safety

This results in undefined behavior when rhs > self.trailing_zeros() || rhs >= i8::BITS i.e. when i8::shr_exact would return None.

1.13.0 (const: 1.47.0) · Source

pub const fn checked_abs(self) -> Option<Self>

Checked absolute value. Computes self.abs(), returning None if self == MIN.

§Examples

assert_eq!((-5i8).checked_abs(), Some(5));
assert_eq!(i8::MIN.checked_abs(), None);

1.91.0 (const: 1.91.0) · Source

pub const fn strict_abs(self) -> Self

Strict absolute value. Computes self.abs(), panicking if self == MIN.

§Panics

§Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

§Examples

assert_eq!((-5i8).strict_abs(), 5);

The following panics because of overflow:

let _ = i8::MIN.strict_abs();

1.34.0 (const: 1.50.0) · Source

pub const fn checked_pow(self, exp: u32) -> Option<Self>

Checked exponentiation. Computes self.pow(exp), returning None if overflow occurred.

§Examples

assert_eq!(8i8.checked_pow(2), Some(64));
assert_eq!(0_i8.checked_pow(0), Some(1));
assert_eq!(i8::MAX.checked_pow(2), None);

1.91.0 (const: 1.91.0) · Source

pub const fn strict_pow(self, exp: u32) -> Self

Strict exponentiation. Computes self.pow(exp), panicking if overflow occurred.

§Panics

§Overflow behavior

This function will always panic on overflow, regardless of whether overflow checks are enabled.

§Examples

assert_eq!(8i8.strict_pow(2), 64);
assert_eq!(0_i8.strict_pow(0), 1);

The following panics because of overflow:

let _ = i8::MAX.strict_pow(2);

1.84.0 (const: 1.84.0) · Source

pub const fn checked_isqrt(self) -> Option<Self>

Returns the integer square root of the number, rounded down.

This function returns the principal (non-negative) square root. For a given number n, although both x and -x satisfy x² = n, this function always returns the non-negative value.

Returns None if self is negative.

§Examples

assert_eq!(10i8.checked_isqrt(), Some(3));

1.0.0 (const: 1.47.0) · Source

pub const fn saturating_add(self, rhs: Self) -> Self

Saturating integer addition. Computes self + rhs, saturating at the numeric bounds instead of overflowing.

§Examples

assert_eq!(100i8.saturating_add(1), 101);
assert_eq!(i8::MAX.saturating_add(100), i8::MAX);
assert_eq!(i8::MIN.saturating_add(-1), i8::MIN);

1.66.0 (const: 1.66.0) · Source

pub const fn saturating_add_unsigned(self, rhs: u8) -> Self

Saturating addition with an unsigned integer. Computes self + rhs, saturating at the numeric bounds instead of overflowing.

§Examples

assert_eq!(1i8.saturating_add_unsigned(2), 3);
assert_eq!(i8::MAX.saturating_add_unsigned(100), i8::MAX);

1.0.0 (const: 1.47.0) · Source

pub const fn saturating_sub(self, rhs: Self) -> Self

Saturating integer subtraction. Computes self - rhs, saturating at the numeric bounds instead of overflowing.

§Examples

assert_eq!(100i8.saturating_sub(127), -27);
assert_eq!(i8::MIN.saturating_sub(100), i8::MIN);
assert_eq!(i8::MAX.saturating_sub(-1), i8::MAX);

1.66.0 (const: 1.66.0) · Source

pub const fn saturating_sub_unsigned(self, rhs: u8) -> Self

Saturating subtraction with an unsigned integer. Computes self - rhs, saturating at the numeric bounds instead of overflowing.

§Examples

assert_eq!(100i8.saturating_sub_unsigned(127), -27);
assert_eq!(i8::MIN.saturating_sub_unsigned(100), i8::MIN);

1.45.0 (const: 1.47.0) · Source

pub const fn saturating_neg(self) -> Self

Saturating integer negation. Computes -self, returning MAX if self == MIN instead of overflowing.

§Examples

assert_eq!(100i8.saturating_neg(), -100);
assert_eq!((-100i8).saturating_neg(), 100);
assert_eq!(i8::MIN.saturating_neg(), i8::MAX);
assert_eq!(i8::MAX.saturating_neg(), i8::MIN + 1);

1.45.0 (const: 1.47.0) · Source

pub const fn saturating_abs(self) -> Self

Saturating absolute value. Computes self.abs(), returning MAX if self == MIN instead of overflowing.

§Examples

assert_eq!(100i8.saturating_abs(), 100);
assert_eq!((-100i8).saturating_abs(), 100);
assert_eq!(i8::MIN.saturating_abs(), i8::MAX);
assert_eq!((i8::MIN + 1).saturating_abs(), i8::MAX);

1.7.0 (const: 1.47.0) · Source

pub const fn saturating_mul(self, rhs: Self) -> Self

Saturating integer multiplication. Computes self * rhs, saturating at the numeric bounds instead of overflowing.

§Examples

assert_eq!(10i8.saturating_mul(12), 120);
assert_eq!(i8::MAX.saturating_mul(10), i8::MAX);
assert_eq!(i8::MIN.saturating_mul(10), i8::MIN);

1.58.0 (const: 1.58.0) · Source

assert_eq!(10i8.wrapping_mul(12), 120);
assert_eq!(11i8.wrapping_mul(12), -124);

1.2.0 (const: 1.52.0) · Source

pub const fn wrapping_div(self, rhs: Self) -> Self

Wrapping (modular) division. Computes self / rhs, wrapping around at the boundary of the type.

The only case where such wrapping can occur is when one divides MIN / -1 on a signed type (where MIN is the negative minimal value for the type); this is equivalent to -MIN, a positive value that is too large to represent in the type. In such a case, this function returns MIN itself.

§Panics

This function will panic if rhs is zero.

§Examples

assert_eq!(100i8.wrapping_div(10), 10);
assert_eq!((-128i8).wrapping_div(-1), -128);

1.38.0 (const: 1.52.0) · Source

pub const fn wrapping_div_euclid(self, rhs: Self) -> Self

Wrapping Euclidean division. Computes self.div_euclid(rhs), wrapping around at the boundary of the type.

Wrapping will only occur in MIN / -1 on a signed type (where MIN is the negative minimal value for the type). This is equivalent to -MIN, a positive value that is too large to represent in the type. In this case, this method returns MIN itself.

§Panics

This function will panic if rhs is zero.

§Examples

assert_eq!(100i8.wrapping_div_euclid(10), 10);
assert_eq!((-128i8).wrapping_div_euclid(-1), -128);

1.2.0 (const: 1.52.0) · Source

pub const fn wrapping_rem(self, rhs: Self) -> Self

Wrapping (modular) remainder. Computes self % rhs, wrapping around at the boundary of the type.

Such wrap-around never actually occurs mathematically; implementation artifacts make x % y invalid for MIN / -1 on a signed type (where MIN is the negative minimal value). In such a case, this function returns 0.

§Panics

This function will panic if rhs is zero.

§Examples

assert_eq!(100i8.wrapping_rem(10), 0);
assert_eq!((-128i8).wrapping_rem(-1), 0);

1.38.0 (const: 1.52.0) · Source

pub const fn wrapping_rem_euclid(self, rhs: Self) -> Self

Wrapping Euclidean remainder. Computes self.rem_euclid(rhs), wrapping around at the boundary of the type.

Wrapping will only occur in MIN % -1 on a signed type (where MIN is the negative minimal value for the type). In this case, this method returns 0.

§Panics

This function will panic if rhs is zero.

§Examples

assert_eq!(100i8.wrapping_rem_euclid(10), 0);
assert_eq!((-128i8).wrapping_rem_euclid(-1), 0);

1.2.0 (const: 1.32.0) · Source

pub const fn wrapping_neg(self) -> Self

Wrapping (modular) negation. Computes -self, wrapping around at the boundary of the type.

The only case where such wrapping can occur is when one negates MIN on a signed type (where MIN is the negative minimal value for the type); this is a positive value that is too large to represent in the type. In such a case, this function returns MIN itself.

§Examples

assert_eq!(100i8.wrapping_neg(), -100);
assert_eq!((-100i8).wrapping_neg(), 100);
assert_eq!(i8::MIN.wrapping_neg(), i8::MIN);

1.2.0 (const: 1.32.0) · Source

pub const fn wrapping_shl(self, rhs: u32) -> Self

Panic-free bitwise shift-left; yields self << mask(rhs), where mask removes any high-order bits of rhs that would cause the shift to exceed the bitwidth of the type.

Beware that, unlike most other wrapping_* methods on integers, this does not give the same result as doing the shift in infinite precision then truncating as needed. The behaviour matches what shift instructions do on many processors, and is what the << operator does when overflow checks are disabled, but numerically it’s weird. Consider, instead, using Self::unbounded_shl which has nicer behaviour.

Note that this is not the same as a rotate-left; the RHS of a wrapping shift-left is restricted to the range of the type, rather than the bits shifted out of the LHS being returned to the other end. The primitive integer types all implement a rotate_left function, which may be what you want instead.

§Examples

assert_eq!((-1_i8).wrapping_shl(7), -128);
assert_eq!(42_i8.wrapping_shl(8), 42);
assert_eq!(42_i8.wrapping_shl(1).wrapping_shl(7), 0);
assert_eq!((-1_i8).wrapping_shl(128), -1);
assert_eq!(5_i8.wrapping_shl(1025), 10);

1.2.0 (const: 1.32.0) · Source

pub const fn wrapping_shr(self, rhs: u32) -> Self

Panic-free bitwise shift-right; yields self >> mask(rhs), where mask removes any high-order bits of rhs that would cause the shift to exceed the bitwidth of the type.

Beware that, unlike most other wrapping_* methods on integers, this does not give the same result as doing the shift in infinite precision then truncating as needed. The behaviour matches what shift instructions do on many processors, and is what the >> operator does when overflow checks are disabled, but numerically it’s weird. Consider, instead, using Self::unbounded_shr which has nicer behaviour.

Note that this is not the same as a rotate-right; the RHS of a wrapping shift-right is restricted to the range of the type, rather than the bits shifted out of the LHS being returned to the other end. The primitive integer types all implement a rotate_right function, which may be what you want instead.

§Examples

assert_eq!((-128_i8).wrapping_shr(7), -1);
assert_eq!(42_i8.wrapping_shr(8), 42);
assert_eq!(42_i8.wrapping_shr(1).wrapping_shr(7), 0);
assert_eq!((-128_i16).wrapping_shr(64), -128);
assert_eq!(10_i8.wrapping_shr(1025), 5);

1.13.0 (const: 1.32.0) · Source

pub const fn wrapping_abs(self) -> Self

Wrapping (modular) absolute value. Computes self.abs(), wrapping around at the boundary of the type.

The only case where such wrapping can occur is when one takes the absolute value of the negative minimal value for the type; this is a positive value that is too large to represent in the type. In such a case, this function returns MIN itself.

§Examples

assert_eq!(100i8.wrapping_abs(), 100);
assert_eq!((-100i8).wrapping_abs(), 100);
assert_eq!(i8::MIN.wrapping_abs(), i8::MIN);
assert_eq!((-128i8).wrapping_abs() as u8, 128);

1.51.0 (const: 1.51.0) · Source

pub const fn unsigned_abs(self) -> u8

Computes the absolute value of self without any wrapping or panicking.

§Examples

assert_eq!(100i8.unsigned_abs(), 100u8);
assert_eq!((-100i8).unsigned_abs(), 100u8);
assert_eq!((-128i8).unsigned_abs(), 128u8);

1.34.0 (const: 1.50.0) · Source

pub const fn wrapping_pow(self, exp: u32) -> Self

Wrapping (modular) exponentiation. Computes self.pow(exp), wrapping around at the boundary of the type.

§Examples

assert_eq!(3i8.wrapping_pow(4), 81);
assert_eq!(3i8.wrapping_pow(5), -13);
assert_eq!(3i8.wrapping_pow(6), -39);
assert_eq!(0_i8.wrapping_pow(0), 1);

1.7.0 (const: 1.32.0) · Source

pub const fn overflowing_add(self, rhs: Self) -> (Self, bool)

Calculates self + rhs.

Returns a tuple of the addition along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would have occurred then the wrapped value is returned (negative if overflowed above MAX, non-negative if below MIN).

§Examples

assert_eq!(5i8.overflowing_add(2), (7, false));
assert_eq!(i8::MAX.overflowing_add(1), (i8::MIN, true));

Source

pub const fn carrying_add(self, rhs: Self, carry: bool) -> (Self, bool)

🔬This is a nightly-only experimental API. (signed_bigint_helpers #151989)

Calculates self + rhs + carry and checks for overflow.

Performs “ternary addition” of two integer operands and a carry-in bit, and returns a tuple of the sum along with a boolean indicating whether an arithmetic overflow would occur. On overflow, the wrapped value is returned.

This allows chaining together multiple additions to create a wider addition, and can be useful for bignum addition. This method should only be used for the most significant word; for the less significant words the unsigned method u8::carrying_add should be used.

The output boolean returned by this method is not a carry flag, and should not be added to a more significant word.

If overflow occurred, the wrapped value is returned (negative if overflowed above MAX, non-negative if below MIN).

If the input carry is false, this method is equivalent to overflowing_add.

§Examples

#![feature(signed_bigint_helpers)]
// Only the most significant word is signed.
//
//   10  MAX    (a = 10 × 2^8 + 2^8 - 1)
// + -5    9    (b = -5 × 2^8 + 9)
// ---------
//    6    8    (sum = 6 × 2^8 + 8)

let (a1, a0): (i8, u8) = (10, u8::MAX);
let (b1, b0): (i8, u8) = (-5, 9);
let carry0 = false;

// u8::carrying_add for the less significant words
let (sum0, carry1) = a0.carrying_add(b0, carry0);
assert_eq!(carry1, true);

// i8::carrying_add for the most significant word
let (sum1, overflow) = a1.carrying_add(b1, carry1);
assert_eq!(overflow, false);

assert_eq!((sum1, sum0), (6, 8));

1.66.0 (const: 1.66.0) · Source

pub const fn overflowing_add_unsigned(self, rhs: u8) -> (Self, bool)

Calculates self + rhs with an unsigned rhs.

Returns a tuple of the addition along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would have occurred then the wrapped value is returned.

§Examples

assert_eq!(1i8.overflowing_add_unsigned(2), (3, false));
assert_eq!((i8::MIN).overflowing_add_unsigned(u8::MAX), (i8::MAX, false));
assert_eq!((i8::MAX - 2).overflowing_add_unsigned(3), (i8::MIN, true));

1.7.0 (const: 1.32.0) · Source

pub const fn overflowing_sub(self, rhs: Self) -> (Self, bool)

Calculates self - rhs.

Returns a tuple of the subtraction along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would have occurred then the wrapped value is returned (negative if overflowed above MAX, non-negative if below MIN).

§Examples

assert_eq!(5i8.overflowing_sub(2), (3, false));
assert_eq!(i8::MIN.overflowing_sub(1), (i8::MAX, true));

Source

pub const fn borrowing_sub(self, rhs: Self, borrow: bool) -> (Self, bool)

🔬This is a nightly-only experimental API. (signed_bigint_helpers #151989)

Calculates self − rhs − borrow and checks for overflow.

Performs “ternary subtraction” by subtracting both an integer operand and a borrow-in bit from self, and returns a tuple of the difference along with a boolean indicating whether an arithmetic overflow would occur. On overflow, the wrapped value is returned.

This allows chaining together multiple subtractions to create a wider subtraction, and can be useful for bignum subtraction. This method should only be used for the most significant word; for the less significant words the unsigned method u8::borrowing_sub should be used.

The output boolean returned by this method is not a borrow flag, and should not be subtracted from a more significant word.

If overflow occurred, the wrapped value is returned (negative if overflowed above MAX, non-negative if below MIN).

If the input borrow is false, this method is equivalent to overflowing_sub.

§Examples

#![feature(signed_bigint_helpers)]
// Only the most significant word is signed.
//
//    6    8    (a = 6 × 2^8 + 8)
// - -5    9    (b = -5 × 2^8 + 9)
// ---------
//   10  MAX    (diff = 10 × 2^8 + 2^8 - 1)

let (a1, a0): (i8, u8) = (6, 8);
let (b1, b0): (i8, u8) = (-5, 9);
let borrow0 = false;

// u8::borrowing_sub for the less significant words
let (diff0, borrow1) = a0.borrowing_sub(b0, borrow0);
assert_eq!(borrow1, true);

// i8::borrowing_sub for the most significant word
let (diff1, overflow) = a1.borrowing_sub(b1, borrow1);
assert_eq!(overflow, false);

assert_eq!((diff1, diff0), (10, u8::MAX));

1.66.0 (const: 1.66.0) · Source

pub const fn overflowing_sub_unsigned(self, rhs: u8) -> (Self, bool)

Calculates self - rhs with an unsigned rhs.

Returns a tuple of the subtraction along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would have occurred then the wrapped value is returned.

§Examples

assert_eq!(1i8.overflowing_sub_unsigned(2), (-1, false));
assert_eq!((i8::MAX).overflowing_sub_unsigned(u8::MAX), (i8::MIN, false));
assert_eq!((i8::MIN + 2).overflowing_sub_unsigned(3), (i8::MAX, true));

1.7.0 (const: 1.32.0) · Source

pub const fn overflowing_mul(self, rhs: Self) -> (Self, bool)

Calculates the multiplication of self and rhs.

Returns a tuple of the multiplication along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would have occurred then the wrapped value is returned.

§Examples

assert_eq!(5i8.overflowing_mul(2), (10, false));
assert_eq!(1_000_000_000i32.overflowing_mul(10), (1410065408, true));

Source

pub const fn carrying_mul(self, rhs: Self, carry: Self) -> (u8, Self)

🔬This is a nightly-only experimental API. (signed_bigint_helpers #151989)

Calculates the “full multiplication” self * rhs + carry without the possibility to overflow.

This returns the low-order (wrapping) bits and the high-order (overflow) bits of the result as two separate values, in that order.

Performs “long multiplication” which takes in an extra amount to add, and may return an additional amount of overflow. This allows for chaining together multiple multiplications to create “big integers” which represent larger values.

§Examples

Please note that this example is shared among integer types, which is why i32 is used.

#![feature(signed_bigint_helpers)]
assert_eq!(5i32.carrying_mul(-2, 0), (4294967286, -1));
assert_eq!(5i32.carrying_mul(-2, 10), (0, 0));
assert_eq!(1_000_000_000i32.carrying_mul(-10, 0), (2884901888, -3));
assert_eq!(1_000_000_000i32.carrying_mul(-10, 10), (2884901898, -3));
assert_eq!(i8::MAX.carrying_mul(i8::MAX, i8::MAX), (i8::MAX.unsigned_abs() + 1, i8::MAX / 2));

Source

pub const fn carrying_mul_add( self, rhs: Self, carry: Self, add: Self, ) -> (u8, Self)

🔬This is a nightly-only experimental API. (signed_bigint_helpers #151989)

Calculates the “full multiplication” self * rhs + carry + add without the possibility to overflow.

This returns the low-order (wrapping) bits and the high-order (overflow) bits of the result as two separate values, in that order.

Performs “long multiplication” which takes in an extra amount to add, and may return an additional amount of overflow. This allows for chaining together multiple multiplications to create “big integers” which represent larger values.

If you only need one carry, then you can use Self::carrying_mul instead.

§Examples

Please note that this example is shared among integer types, which is why i32 is used.

#![feature(signed_bigint_helpers)]
assert_eq!(5i32.carrying_mul_add(-2, 0, 0), (4294967286, -1));
assert_eq!(5i32.carrying_mul_add(-2, 10, 10), (10, 0));
assert_eq!(1_000_000_000i32.carrying_mul_add(-10, 0, 0), (2884901888, -3));
assert_eq!(1_000_000_000i32.carrying_mul_add(-10, 10, 10), (2884901908, -3));
assert_eq!(i8::MAX.carrying_mul_add(i8::MAX, i8::MAX, i8::MAX), (u8::MAX, i8::MAX / 2));

1.7.0 (const: 1.52.0) · Source

pub const fn overflowing_div(self, rhs: Self) -> (Self, bool)

Calculates the divisor when self is divided by rhs.

Returns a tuple of the divisor along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would occur then self is returned.

§Panics

This function will panic if rhs is zero.

§Examples

assert_eq!(5i8.overflowing_div(2), (2, false));
assert_eq!(i8::MIN.overflowing_div(-1), (i8::MIN, true));

1.38.0 (const: 1.52.0) · Source

pub const fn overflowing_div_euclid(self, rhs: Self) -> (Self, bool)

Calculates the quotient of Euclidean division self.div_euclid(rhs).

Returns a tuple of the divisor along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would occur then self is returned.

§Panics

This function will panic if rhs is zero.

§Examples

assert_eq!(5i8.overflowing_div_euclid(2), (2, false));
assert_eq!(i8::MIN.overflowing_div_euclid(-1), (i8::MIN, true));

1.7.0 (const: 1.52.0) · Source

pub const fn overflowing_rem(self, rhs: Self) -> (Self, bool)

Calculates the remainder when self is divided by rhs.

Returns a tuple of the remainder after dividing along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would occur then 0 is returned.

§Panics

This function will panic if rhs is zero.

§Examples

assert_eq!(5i8.overflowing_rem(2), (1, false));
assert_eq!(i8::MIN.overflowing_rem(-1), (0, true));

1.38.0 (const: 1.52.0) · Source

pub const fn overflowing_rem_euclid(self, rhs: Self) -> (Self, bool)

Overflowing Euclidean remainder. Calculates self.rem_euclid(rhs).

Returns a tuple of the remainder after dividing along with a boolean indicating whether an arithmetic overflow would occur. If an overflow would occur then 0 is returned.

§Panics

This function will panic if rhs is zero.

§Examples

assert_eq!(5i8.overflowing_rem_euclid(2), (1, false));
assert_eq!(i8::MIN.overflowing_rem_euclid(-1), (0, true));

1.7.0 (const: 1.32.0) · Source

pub const fn overflowing_neg(self) -> (Self, bool)

Negates self, overflowing if this is equal to the minimum value.

Returns a tuple of the negated version of self along with a boolean indicating whether an overflow happened. If self is the minimum value (e.g., i32::MIN for values of type i32), then the minimum value will be returned again and true will be returned for an overflow happening.

§Examples

assert_eq!(2i8.overflowing_neg(), (-2, false));
assert_eq!(i8::MIN.overflowing_neg(), (i8::MIN, true));

1.7.0 (const: 1.32.0) · Source

pub const fn overflowing_shl(self, rhs: u32) -> (Self, bool)

Shifts self left by rhs bits.

Returns a tuple of the shifted version of self along with a boolean indicating whether the shift value was larger than or equal to the number of bits. If the shift value is too large, then value is masked (N-1) where N is the number of bits, and this value is then used to perform the shift.

§Examples

assert_eq!(0x1i8.overflowing_shl(4), (0x10, false));
assert_eq!(0x1i32.overflowing_shl(36), (0x10, true));
assert_eq!(0x10i8.overflowing_shl(7), (0, false));

1.7.0 (const: 1.32.0) · Source

pub const fn overflowing_shr(self, rhs: u32) -> (Self, bool)

Shifts self right by rhs bits.

Returns a tuple of the shifted version of self along with a boolean indicating whether the shift value was larger than or equal to the number of bits. If the shift value is too large, then value is masked (N-1) where N is the number of bits, and this value is then used to perform the shift.

§Examples

assert_eq!(0x10i8.overflowing_shr(4), (0x1, false));
assert_eq!(0x10i32.overflowing_shr(36), (0x1, true));

1.13.0 (const: 1.32.0) · Source

pub const fn overflowing_abs(self) -> (Self, bool)

Computes the absolute value of self.

Returns a tuple of the absolute version of self along with a boolean indicating whether an overflow happened. If self is the minimum value (e.g., i8::MIN for values of type i8), then the minimum value will be returned again and true will be returned for an overflow happening.

§Examples

assert_eq!(10i8.overflowing_abs(), (10, false));
assert_eq!((-10i8).overflowing_abs(), (10, false));
assert_eq!((i8::MIN).overflowing_abs(), (i8::MIN, true));

1.34.0 (const: 1.50.0) · Source

pub const fn overflowing_pow(self, exp: u32) -> (Self, bool)

Raises self to the power of exp, using exponentiation by squaring.

Returns a tuple of the exponentiation along with a bool indicating whether an overflow happened.

§Examples

assert_eq!(3i8.overflowing_pow(4), (81, false));
assert_eq!(0_i8.overflowing_pow(0), (1, false));
assert_eq!(3i8.overflowing_pow(5), (-13, true));

1.0.0 (const: 1.50.0) · Source

pub const fn pow(self, exp: u32) -> Self

Raises self to the power of exp, using exponentiation by squaring.

§Examples

let x: i8 = 2; // or any other integer type

assert_eq!(x.pow(5), 32);
assert_eq!(0_i8.pow(0), 1);

1.84.0 (const: 1.84.0) · Source

pub const fn isqrt(self) -> Self

Returns the integer square root of the number, rounded down.

This function returns the principal (non-negative) square root. For a given number n, although both x and -x satisfy x² = n, this function always returns the non-negative value.

§Panics

This function will panic if self is negative.

§Examples

assert_eq!(10i8.isqrt(), 3);

1.38.0 (const: 1.52.0) · Source

pub const fn div_euclid(self, rhs: Self) -> Self

Calculates the quotient of Euclidean division of self by rhs.

This computes the integer q such that self = q * rhs + r, with r = self.rem_euclid(rhs) and 0 <= r < abs(rhs).

In other words, the result is self / rhs rounded to the integer q such that self >= q * rhs. If self > 0, this is equal to rounding towards zero (the default in Rust); if self < 0, this is equal to rounding away from zero (towards +/- infinity). If rhs > 0, this is equal to rounding towards -infinity; if rhs < 0, this is equal to rounding towards +infinity.

§Panics

This function will panic if rhs is zero or if self is Self::MIN and rhs is -1. This behavior is not affected by the overflow-checks flag.

§Examples

let a: i8 = 7; // or any other integer type
let b = 4;

assert_eq!(a.div_euclid(b), 1); // 7 >= 4 * 1
assert_eq!(a.div_euclid(-b), -1); // 7 >= -4 * -1
assert_eq!((-a).div_euclid(b), -2); // -7 >= 4 * -2
assert_eq!((-a).div_euclid(-b), 2); // -7 >= -4 * 2

1.38.0 (const: 1.52.0) · Source

pub const fn rem_euclid(self, rhs: Self) -> Self

Calculates the least nonnegative remainder of self when divided by rhs.

This is done as if by the Euclidean division algorithm – given r = self.rem_euclid(rhs), the result satisfies self = rhs * self.div_euclid(rhs) + r and 0 <= r < abs(rhs).

§Panics

This function will panic if rhs is zero or if self is Self::MIN and rhs is -1. This behavior is not affected by the overflow-checks flag.

§Examples

let a: i8 = 7; // or any other integer type
let b = 4;

assert_eq!(a.rem_euclid(b), 3);
assert_eq!((-a).rem_euclid(b), 1);
assert_eq!(a.rem_euclid(-b), 3);
assert_eq!((-a).rem_euclid(-b), 1);

This will panic:

let _ = i8::MIN.rem_euclid(-1);

Source

pub const fn div_floor(self, rhs: Self) -> Self

🔬This is a nightly-only experimental API. (int_roundings #88581)

Calculates the quotient of self and rhs, rounding the result towards negative infinity.

§Panics

This function will panic if rhs is zero or if self is Self::MIN and rhs is -1. This behavior is not affected by the overflow-checks flag.

§Examples

#![feature(int_roundings)]
let a: i8 = 8;
let b = 3;

assert_eq!(a.div_floor(b), 2);
assert_eq!(a.div_floor(-b), -3);
assert_eq!((-a).div_floor(b), -3);
assert_eq!((-a).div_floor(-b), 2);

Source

pub const fn div_ceil(self, rhs: Self) -> Self

🔬This is a nightly-only experimental API. (int_roundings #88581)

Calculates the quotient of self and rhs, rounding the result towards positive infinity.

§Panics

This function will panic if rhs is zero or if self is Self::MIN and rhs is -1. This behavior is not affected by the overflow-checks flag.

§Examples

#![feature(int_roundings)]
let a: i8 = 8;
let b = 3;

assert_eq!(a.div_ceil(b), 3);
assert_eq!(a.div_ceil(-b), -2);
assert_eq!((-a).div_ceil(b), -2);
assert_eq!((-a).div_ceil(-b), 3);

Source

pub const fn next_multiple_of(self, rhs: Self) -> Self

🔬This is a nightly-only experimental API. (int_roundings #88581)

If rhs is positive, calculates the smallest value greater than or equal to self that is a multiple of rhs. If rhs is negative, calculates the largest value less than or equal to self that is a multiple of rhs.

§Panics

This function will panic if rhs is zero.

§Overflow behavior

On overflow, this function will panic if overflow checks are enabled (default in debug mode) and wrap if overflow checks are disabled (default in release mode).

§Examples

#![feature(int_roundings)]
assert_eq!(16_i8.next_multiple_of(8), 16);
assert_eq!(23_i8.next_multiple_of(8), 24);
assert_eq!(16_i8.next_multiple_of(-8), 16);
assert_eq!(23_i8.next_multiple_of(-8), 16);
assert_eq!((-16_i8).next_multiple_of(8), -16);
assert_eq!((-23_i8).next_multiple_of(8), -16);
assert_eq!((-16_i8).next_multiple_of(-8), -16);
assert_eq!((-23_i8).next_multiple_of(-8), -24);

Source

pub const fn checked_next_multiple_of(self, rhs: Self) -> Option<Self>

🔬This is a nightly-only experimental API. (int_roundings #88581)

If rhs is positive, calculates the smallest value greater than or equal to self that is a multiple of rhs. If rhs is negative, calculates the largest value less than or equal to self that is a multiple of rhs. Returns None if rhs is zero or the operation would result in overflow.

§Examples

#![feature(int_roundings)]
assert_eq!(16_i8.checked_next_multiple_of(8), Some(16));
assert_eq!(23_i8.checked_next_multiple_of(8), Some(24));
assert_eq!(16_i8.checked_next_multiple_of(-8), Some(16));
assert_eq!(23_i8.checked_next_multiple_of(-8), Some(16));
assert_eq!((-16_i8).checked_next_multiple_of(8), Some(-16));
assert_eq!((-23_i8).checked_next_multiple_of(8), Some(-16));
assert_eq!((-16_i8).checked_next_multiple_of(-8), Some(-16));
assert_eq!((-23_i8).checked_next_multiple_of(-8), Some(-24));
assert_eq!(1_i8.checked_next_multiple_of(0), None);
assert_eq!(i8::MAX.checked_next_multiple_of(2), None);

1.67.0 (const: 1.67.0) · Source

pub const fn ilog(self, base: Self) -> u32

Returns the logarithm of the number with respect to an arbitrary base, rounded down.

This method might not be optimized owing to implementation details; ilog2 can produce results more efficiently for base 2, and ilog10 can produce results more efficiently for base 10.

§Panics

This function will panic if self is less than or equal to zero, or if base is less than 2.

§Examples

assert_eq!(5i8.ilog(5), 1);

1.67.0 (const: 1.67.0) · Source

pub const fn ilog2(self) -> u32

Returns the base 2 logarithm of the number, rounded down.

§Panics

This function will panic if self is less than or equal to zero.

§Examples

assert_eq!(2i8.ilog2(), 1);

1.67.0 (const: 1.67.0) · Source

pub const fn ilog10(self) -> u32

Returns the base 10 logarithm of the number, rounded down.

§Panics

This function will panic if self is less than or equal to zero.

§Example

assert_eq!(10i8.ilog10(), 1);

1.67.0 (const: 1.67.0) · Source

pub const fn checked_ilog(self, base: Self) -> Option<u32>

Returns the logarithm of the number with respect to an arbitrary base, rounded down.

Returns None if the number is negative or zero, or if the base is not at least 2.

This method might not be optimized owing to implementation details; checked_ilog2 can produce results more efficiently for base 2, and checked_ilog10 can produce results more efficiently for base 10.

§Examples

assert_eq!(5i8.checked_ilog(5), Some(1));

1.67.0 (const: 1.67.0) · Source

pub const fn checked_ilog2(self) -> Option<u32>

Returns the base 2 logarithm of the number, rounded down.

Returns None if the number is negative or zero.

Note that for non-negative numbers, this is equivalent to highest_one.

§Examples

assert_eq!(2i8.checked_ilog2(), Some(1));

1.67.0 (const: 1.67.0) · Source

pub const fn checked_ilog10(self) -> Option<u32>

Returns the base 10 logarithm of the number, rounded down.

Returns None if the number is negative or zero.

§Example

assert_eq!(10i8.checked_ilog10(), Some(1));

1.0.0 (const: 1.32.0) · Source

pub const fn abs(self) -> Self

Computes the absolute value of self.

§Overflow behavior

The absolute value of i8::MIN cannot be represented as an i8, and attempting to calculate it will cause an overflow. This means that code in debug mode will trigger a panic on this case and optimized code will return i8::MIN without a panic. If you do not want this behavior, consider using unsigned_abs instead.

§Examples

assert_eq!(10i8.abs(), 10);
assert_eq!((-10i8).abs(), 10);

1.60.0 (const: 1.60.0) · Source

pub const fn abs_diff(self, other: Self) -> u8

Computes the absolute difference between self and other.

This function always returns the correct answer without overflow or panics by returning an unsigned integer.

§Examples

assert_eq!(100i8.abs_diff(80), 20u8);
assert_eq!(100i8.abs_diff(110), 10u8);
assert_eq!((-100i8).abs_diff(80), 180u8);
assert_eq!((-100i8).abs_diff(-120), 20u8);
assert_eq!(i8::MIN.abs_diff(i8::MAX), u8::MAX);

1.0.0 (const: 1.47.0) · Source

pub const fn signum(self) -> Self

Returns a number representing sign of self.

0 if the number is zero
1 if the number is positive
-1 if the number is negative

§Examples

assert_eq!(10i8.signum(), 1);
assert_eq!(0i8.signum(), 0);
assert_eq!((-10i8).signum(), -1);

1.0.0 (const: 1.32.0) · Source

pub const fn is_positive(self) -> bool

Returns true if self is positive and false if the number is zero or negative.

§Examples

assert!(10i8.is_positive());
assert!(!(-10i8).is_positive());

1.0.0 (const: 1.32.0) · Source

pub const fn is_negative(self) -> bool

Returns true if self is negative and false if the number is zero or positive.

§Examples

assert!((-10i8).is_negative());
assert!(!10i8.is_negative());

1.32.0 (const: 1.44.0) · Source

pub const fn to_be_bytes(self) -> [u8; 1]

Returns the memory representation of this integer as a byte array in big-endian (network) byte order.

Note: This function is meaningless on i8. Byte order does not exist as a concept for byte-sized integers. This function is only provided in symmetry with larger integer types. You can cast from and to u8 using cast_signed and cast_unsigned.

§Examples

let bytes = 0x12i8.to_be_bytes();
assert_eq!(bytes, [0x12]);

1.32.0 (const: 1.44.0) · Source

pub const fn to_le_bytes(self) -> [u8; 1]

Returns the memory representation of this integer as a byte array in little-endian byte order.

Note: This function is meaningless on i8. Byte order does not exist as a concept for byte-sized integers. This function is only provided in symmetry with larger integer types. You can cast from and to u8 using cast_signed and cast_unsigned.

§Examples

let bytes = 0x12i8.to_le_bytes();
assert_eq!(bytes, [0x12]);

1.32.0 (const: 1.44.0) · Source

pub const fn to_ne_bytes(self) -> [u8; 1]

Returns the memory representation of this integer as a byte array in native byte order.

As the target platform’s native endianness is used, portable code should use to_be_bytes or to_le_bytes, as appropriate, instead.

Note: This function is meaningless on i8. Byte order does not exist as a concept for byte-sized integers. This function is only provided in symmetry with larger integer types. You can cast from and to u8 using cast_signed and cast_unsigned.

§Examples

let bytes = 0x12i8.to_ne_bytes();
assert_eq!(
    bytes,
    if cfg!(target_endian = "big") {
        [0x12]
    } else {
        [0x12]
    }
);

1.32.0 (const: 1.44.0) · Source

pub const fn from_be_bytes(bytes: [u8; 1]) -> Self

Creates an integer value from its representation as a byte array in big endian.

Note: This function is meaningless on i8. Byte order does not exist as a concept for byte-sized integers. This function is only provided in symmetry with larger integer types. You can cast from and to u8 using cast_signed and cast_unsigned.

§Examples

let value = i8::from_be_bytes([0x12]);
assert_eq!(value, 0x12);

When starting from a slice rather than an array, fallible conversion APIs can be used:

fn read_be_i8(input: &mut &[u8]) -> i8 {
    let (int_bytes, rest) = input.split_at(size_of::<i8>());
    *input = rest;
    i8::from_be_bytes(int_bytes.try_into().unwrap())
}

1.32.0 (const: 1.44.0) · Source

pub const fn from_le_bytes(bytes: [u8; 1]) -> Self

Creates an integer value from its representation as a byte array in little endian.

Note: This function is meaningless on i8. Byte order does not exist as a concept for byte-sized integers. This function is only provided in symmetry with larger integer types. You can cast from and to u8 using cast_signed and cast_unsigned.

§Examples

let value = i8::from_le_bytes([0x12]);
assert_eq!(value, 0x12);

When starting from a slice rather than an array, fallible conversion APIs can be used:

fn read_le_i8(input: &mut &[u8]) -> i8 {
    let (int_bytes, rest) = input.split_at(size_of::<i8>());
    *input = rest;
    i8::from_le_bytes(int_bytes.try_into().unwrap())
}

1.32.0 (const: 1.44.0) · Source

pub const fn from_ne_bytes(bytes: [u8; 1]) -> Self

Creates an integer value from its memory representation as a byte array in native endianness.

As the target platform’s native endianness is used, portable code likely wants to use from_be_bytes or from_le_bytes, as appropriate instead.

Note: This function is meaningless on i8. Byte order does not exist as a concept for byte-sized integers. This function is only provided in symmetry with larger integer types. You can cast from and to u8 using cast_signed and cast_unsigned.

§Examples

let value = i8::from_ne_bytes(if cfg!(target_endian = "big") {
    [0x12]
} else {
    [0x12]
});
assert_eq!(value, 0x12);

When starting from a slice rather than an array, fallible conversion APIs can be used:

fn read_ne_i8(input: &mut &[u8]) -> i8 {
    let (int_bytes, rest) = input.split_at(size_of::<i8>());
    *input = rest;
    i8::from_ne_bytes(int_bytes.try_into().unwrap())
}

1.0.0 (const: 1.32.0) · Source

pub const fn min_value() -> Self

👎Deprecating in a future version:

replaced by the MIN associated constant on this type

New code should prefer to use i8::MIN instead.

Returns the smallest value that can be represented by this integer type.

1.0.0 (const: 1.32.0) · Source

pub const fn max_value() -> Self

👎Deprecating in a future version:

replaced by the MAX associated constant on this type

New code should prefer to use i8::MAX instead.

Returns the largest value that can be represented by this integer type.

Source

pub fn clamp_magnitude(self, limit: u8) -> Self

🔬This is a nightly-only experimental API. (clamp_magnitude #148519)

Clamps this number to a symmetric range centred around zero.

The method clamps the number’s magnitude (absolute value) to be at most limit.

This is functionally equivalent to self.clamp(-limit, limit), but is more explicit about the intent.

§Examples

#![feature(clamp_magnitude)]
assert_eq!(120i8.clamp_magnitude(100), 100);
assert_eq!(-120i8.clamp_magnitude(100), -100);
assert_eq!(80i8.clamp_magnitude(100), 80);
assert_eq!(-80i8.clamp_magnitude(100), -80);

Source

pub const fn truncate<Target>(self) -> Target
where Self: TruncateTarget<Target>,

🔬This is a nightly-only experimental API. (integer_widen_truncate #154330)

Truncate an integer to an integer of the same size or smaller, preserving the least significant bits.

§Examples

#![feature(integer_widen_truncate)]
assert_eq!(120i8, 120i8.truncate());
assert_eq!(-120i8, (-120i8).truncate());
assert_eq!(120i8, 376i32.truncate());

Source

pub const fn saturating_truncate<Target>(self) -> Target
where Self: TruncateTarget<Target>,

🔬This is a nightly-only experimental API. (integer_widen_truncate #154330)

Truncate an integer to an integer of the same size or smaller, saturating at numeric bounds instead of truncating.

§Examples

#![feature(integer_widen_truncate)]
assert_eq!(120i8, 120i8.saturating_truncate());
assert_eq!(-120i8, (-120i8).saturating_truncate());
assert_eq!(127i8, 376i32.saturating_truncate());
assert_eq!(-128i8, (-1000i32).saturating_truncate());

Source

pub const fn checked_truncate<Target>(self) -> Option<Target>
where Self: TruncateTarget<Target>,

🔬This is a nightly-only experimental API. (integer_widen_truncate #154330)

Truncate an integer to an integer of the same size or smaller, returning None if the value is outside the bounds of the smaller type.

§Examples

#![feature(integer_widen_truncate)]
assert_eq!(Some(120i8), 120i8.checked_truncate());
assert_eq!(Some(-120i8), (-120i8).checked_truncate());
assert_eq!(None, 376i32.checked_truncate::<i8>());
assert_eq!(None, (-1000i32).checked_truncate::<i8>());

Source

pub const fn widen<Target>(self) -> Target
where Self: WidenTarget<Target>,

🔬This is a nightly-only experimental API. (integer_widen_truncate #154330)

Widen to an integer of the same size or larger, preserving its value.

§Examples

#![feature(integer_widen_truncate)]
assert_eq!(120i128, 120i8.widen());
assert_eq!(-120i128, (-120i8).widen());

Source

pub const fn saturating_cast<T: BoundedCastFromInt<Self>>(self) -> T

🔬This is a nightly-only experimental API. (integer_casts #157388)

Converts self to the target integer type, saturating at the numeric bounds instead of overflowing.

§Examples

#![feature(integer_casts)]
assert_eq!(i8::MAX, i8::MAX.saturating_cast());
assert_eq!(i8::MIN, i8::MIN.saturating_cast());
assert_eq!(42u8, 42i8.saturating_cast());
assert_eq!(0u8, (-42i8).saturating_cast());

Source

pub const fn wrapping_cast<T: BoundedCastFromInt<Self>>(self) -> T

🔬This is a nightly-only experimental API. (integer_casts #157388)

Converts self to the target integer type, wrapping around at the boundary of the target type.

§Examples

#![feature(integer_casts)]
assert_eq!(i8::MAX as i8, i8::MAX.wrapping_cast());
assert_eq!(i8::MIN as i8, i8::MIN.wrapping_cast());
assert_eq!(42u8, 42i8.wrapping_cast());
assert_eq!(u8::MAX - 41, (-42i8).wrapping_cast());

Source

pub const fn checked_cast<T: CheckedCastFromInt<Self>>(self) -> Option<T>

🔬This is a nightly-only experimental API. (integer_casts #157388)

Converts self to the target integer type, returning None if the value is not representable by the target type.

§Examples

#![feature(integer_casts)]
assert_eq!(Some(42u8), 42i8.checked_cast());
assert_eq!((-42i8).checked_cast::<u8>(), None);

Source

pub const fn strict_cast<T: CheckedCastFromInt<Self>>(self) -> T

🔬This is a nightly-only experimental API. (integer_casts #157388)

Converts self to the target integer type, panicking if the value is not representable by the target type.

§Panics

This function will panic if the value is not representable by the target type.

§Examples

#![feature(integer_casts)]
assert_eq!(42u8, 42i8.strict_cast());

The following will panic:

#![feature(integer_casts)]
let _ = (-42i8).strict_cast::<u8>();

Source

pub const unsafe fn unchecked_cast<T: CheckedCastFromInt<Self>>(self) -> T

🔬This is a nightly-only experimental API. (integer_casts #157388)

Converts self to the target integer type, assuming the value is representable by the target type.

§Safety

This results in undefined behavior if the integer value of self is bigger than T::MAX, or smaller than T::MIN, where T is the target type.

1.87.0 (const: 1.87.0) · Source

pub const fn midpoint(self, rhs: i8) -> i8

Calculates the midpoint (average) between self and rhs.

midpoint(a, b) is (a + b) / 2 as if it were performed in a sufficiently-large signed integral type. This implies that the result is always rounded towards zero and that no overflow will ever occur.

§Examples

assert_eq!(0i8.midpoint(4), 2);
assert_eq!((-1i8).midpoint(2), 0);
assert_eq!((-7i8).midpoint(0), -3);
assert_eq!(0i8.midpoint(-7), -3);
assert_eq!(0i8.midpoint(7), 3);

Source

pub const fn widening_mul(self, rhs: Self) -> i16

🔬This is a nightly-only experimental API. (widening_mul #152016)

Widening multiplication. Computes self * rhs, widening to a larger integer.

The returned value is always exact and can never overflow.

Note that this method is semantically equivalent to carrying_mul with a carry of zero, with the latter instead returning a tuple denoting the low and high parts of the result. Consider using it instead if you need interoperability with other big int helper functions, or if this method isn’t available for a given type.

§Examples

#![feature(widening_mul)]

assert_eq!(i8::MAX.widening_mul(0_i8), 0);
assert_eq!(i8::MAX.widening_mul(i8::MAX), i8::MAX as i16 * i8::MAX as i16);

Source §

impl i8

1.0.0 (const: 1.82.0) · Source

pub const fn from_str_radix(src: &str, radix: u32) -> Result<i8, ParseIntError>

Parses an integer from a string slice with digits in a given base.

The string is expected to be an optional + or - sign followed by only digits. Leading and trailing non-digit characters (including whitespace) represent an error. Underscores (which are accepted in Rust literals) also represent an error.

Digits are a subset of these characters, depending on radix:

0-9
a-z
A-Z

§Panics

This function panics if radix is not in the range from 2 to 36.

§See also

If the string to be parsed is in base 10 (decimal), from_str or str::parse can also be used.

§Examples

assert_eq!(i8::from_str_radix("A", 16), Ok(10));

Trailing space returns error:

assert!(i8::from_str_radix("1 ", 10).is_err());

Source

pub const fn from_ascii(src: &[u8]) -> Result<i8, ParseIntError>

🔬This is a nightly-only experimental API. (int_from_ascii #134821)

Parses an integer from an ASCII-byte slice with decimal digits.

The characters are expected to be an optional + or - sign followed by only digits. Leading and trailing non-digit characters (including whitespace) represent an error. Underscores (which are accepted in Rust literals) also represent an error.

§Examples

#![feature(int_from_ascii)]

assert_eq!(i8::from_ascii(b"+10"), Ok(10));

Trailing space returns error:

assert!(i8::from_ascii(b"1 ").is_err());

Source

pub const fn from_ascii_radix( src: &[u8], radix: u32, ) -> Result<i8, ParseIntError>

🔬This is a nightly-only experimental API. (int_from_ascii #134821)

Parses an integer from an ASCII-byte slice with digits in a given base.

The characters are expected to be an optional + or - sign followed by only digits. Leading and trailing non-digit characters (including whitespace) represent an error. Underscores (which are accepted in Rust literals) also represent an error.

Digits are a subset of these characters, depending on radix:

0-9
a-z
A-Z

§Panics

This function panics if radix is not in the range from 2 to 36.

§Examples

#![feature(int_from_ascii)]

assert_eq!(i8::from_ascii_radix(b"A", 16), Ok(10));

Trailing space returns error:

assert!(i8::from_ascii_radix(b"1 ", 10).is_err());

Source §

impl i8

1.98.0 · Source

pub fn format_into(self, buf: &mut NumBuffer<Self>) -> &str

Allows users to write an integer (in signed decimal format) into a variable buf of type NumBuffer that is passed by the caller by mutable reference.

§Examples

use core::fmt::NumBuffer;

let n = 0i8;
let mut buf = NumBuffer::new();
assert_eq!(n.format_into(&mut buf), "0");

let n1 = 32i8;
assert_eq!(n1.format_into(&mut buf), "32");

let n2 = i8 :: MAX;
assert_eq!(n2.format_into(&mut buf), i8 :: MAX.to_string());

fn carrying_mul_add(self, a: Self, b: Self, c: Self) -> (u8, i8)

🔬This is a nightly-only experimental API. (core_intrinsics_fallbacks)

fn clone_from(&mut self, source: &Self)
where Self:,

Performs copy-assignment from source. Read more

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impl ConstParamTy_ for i8

1.0.0 · Source§

impl Distribution<i8> for RangeFull

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fn sample(&self, source: &mut (impl Rng + ?Sized)) -> i8

🔬This is a nightly-only experimental API. (random #130703)

Samples a random value from the distribution, using the specified random source.

1.0.0 (const: unstable) · Source§

impl Div for i8

This operation rounds towards zero, truncating any fractional part of the exact result.

§Panics

1.28.0 (const: unstable) · Source§

impl From<bool> for i8

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fn from(b: bool) -> Self

Converts from bool to i8 , by turning false into 0 and true into 1.

§Examples

assert_eq!(i8::from(false), 0);

assert_eq!(i8::from(true), 1);

type Buf = [MaybeUninit<u8>; 4]

🔬This is a nightly-only experimental API. (fmt_internals)

fn max(self, other: Self) -> Self
where Self: Sized,

Compares and returns the maximum of two values. Read more

1.21.0 (const: unstable) · Source§

fn min(self, other: Self) -> Self
where Self: Sized,

Compares and returns the minimum of two values. Read more

1.0.0 (const: unstable) · Source§

impl PartialEq for i8

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fn eq(&self, other: &Self) -> bool

Tests for self and other values to be equal, and is used by ==.

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fn ne(&self, other: &Self) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

1.0.0 (const: unstable) · Source§

1.95.0 (const: unstable) · Source§

impl TryFrom<i8> for bool

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fn try_from(i: i8) -> Result<Self, Self::Error>

Tries to create a bool from an integer type. Returns an error if the integer is not 0 or 1.

§Examples

assert_eq!(bool::try_from(0_i8), Ok(false));

assert_eq!(bool::try_from(1_i8), Ok(true));

assert!(bool::try_from(2_i8).is_err());

1.0.0 · Source§

impl UpperHex for i8

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Format signed integers in the two’s-complement form.

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impl UseCloned for i8

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impl ZeroablePrimitive for i8

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type NonZeroInner = NonZeroI8Inner

🔬This is a nightly-only experimental API. (nonzero_internals)

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more

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impl<T> BitOr<NonZero<T>> for T
where T: ZeroablePrimitive + BitOr<Output = T>,

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type Output = NonZero<T>

The resulting type after applying the | operator.

impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

fn try_from(value: U) -> Result<T, <T as TryFrom>::Error>

Performs the conversion.

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impl<T, U> TryInto for T
where U: TryFrom<T>,

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type Error = >::Error

The type returned in the event of a conversion error.

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fn try_into(self) -> Result<U, >::Error>

Performs the conversion.

Primitive Type i8 Copy item path

Implementations§

impl i8

pub const MIN: Self

§Examples

pub const MAX: Self

§Examples

pub const BITS: u32 = u8::BITS

§Examples

pub const fn count_ones(self) -> u32

§Examples

pub const fn count_zeros(self) -> u32

§Examples

pub const fn leading_zeros(self) -> u32

§Examples

pub const fn trailing_zeros(self) -> u32

§Examples

pub const fn leading_ones(self) -> u32

§Examples

pub const fn trailing_ones(self) -> u32

§Examples

pub const fn isolate_highest_one(self) -> Self

§Examples

pub const fn isolate_lowest_one(self) -> Self

§Examples

pub const fn highest_one(self) -> Option<u32>

§Examples

pub const fn lowest_one(self) -> Option<u32>

§Examples

pub const fn cast_unsigned(self) -> u8

§Examples

pub const fn saturating_cast_unsigned(self) -> u8

§Examples

pub const fn checked_cast_unsigned(self) -> Option<u8>

§Examples

pub const fn strict_cast_unsigned(self) -> u8

§Examples

pub const fn rotate_left(self, n: u32) -> Self

§Examples

pub const fn rotate_right(self, n: u32) -> Self

§Examples

pub const fn swap_bytes(self) -> Self

§Examples

pub const fn reverse_bits(self) -> Self

§Examples

pub const fn from_be(x: Self) -> Self

§Examples

pub const fn from_le(x: Self) -> Self

§Examples

pub const fn to_be(self) -> Self

§Examples

pub const fn to_le(self) -> Self

§Examples

pub const fn checked_add(self, rhs: Self) -> Option<Self>

§Examples

pub const fn strict_add(self, rhs: Self) -> Self

§Panics

§Overflow behavior

§Examples

pub const unsafe fn unchecked_add(self, rhs: Self) -> Self

§Safety

pub const fn checked_add_unsigned(self, rhs: u8) -> Option<Self>

§Examples

pub const fn strict_add_unsigned(self, rhs: u8) -> Self

§Panics

§Overflow behavior

§Examples

pub const fn checked_sub(self, rhs: Self) -> Option<Self>

§Examples

pub const fn strict_sub(self, rhs: Self) -> Self

§Panics

§Overflow behavior

§Examples

pub const unsafe fn unchecked_sub(self, rhs: Self) -> Self

§Safety

pub const fn checked_sub_unsigned(self, rhs: u8) -> Option<Self>

§Examples

pub const fn strict_sub_unsigned(self, rhs: u8) -> Self

§Panics

§Overflow behavior

Primitive Type i8