Output of C programs | Set 55

1. What will be the output of the following program? C

#include <stdio.h>
int main()
{
    int a = 03489;
    printf("%d", a);
    return (0);
}

Options: 1. 1865 2. runtime error 3. Syntax error 4. 0

 The answer is option(3).
Explanation:

Any integral value prefix with 0 acts as octal number but the allowed digits is 0 to 7. But here 8 and 9 is there, which result in syntax error. 2. What will be the output of the following program? C

#include <stdio.h>
int main()
{
    char c;
    int i;
    c = 'B';
    i = c - 'A';
    printf("%d", i);
    return (0);
}

Options: 1. 5 2. 1 3. incompatible type declaration 4. -5

The answer is option(2).

Explanation : Here i declared as integer. So, it will manipulate the ASCII values.Since the ASCII value of B is 66 and ASCII value of A is 65. Therefore i = c-'A' = 1. 3. What will be the output of the following program? C

#include <stdio.h>
int main()
{
    printf("GEEKS");
    main();
    return (0);
}

Options: 1. GEEKS 2. run-time error 3. GEEKS infinitely 4. compile time error

 The answer is option(3).

Explanation:Because main() function is calling itself repeatedly. 4. what will be the output of the following program? CPP

#include <stdio.h>
int main()
{
    int n, i = 5;
    n = - - i--;
    printf("%d%d", n, i);
    return (0);
}

Options: 1. 54 2. 44 3. 45 4. 55

 The answer is option(1).

Explanation:Here minus*minus acts as plus before the i in the statement n=- -i--. Reference: https://www.geeksforgeeks.org/c/unary-operators-cc/ 5. what will be the output of the following program? CPP

#include <stdio.h>
int main()
{
    int a = 10;
    printf("%d", a++ * a++);
    return (0);
}

Options: 1. 100 2. 110 3. 105 4. No output

 The answer is option(2).

Explanation:Here a++ is post increment. so when it gets a++ then for the value of a changed to 11 in a buffer but still a=10. when it gets called one more time, a will be 11. so it will be 11*10=110. 6. what will be the output of the following program? CPP

#include <stdio.h>
int main()
{
    int a = 20, b = 8, c;
    c = a != 5 || b == 4;
    printf("c=%d", c);
    return (0);
}

Options: 1. c=0 2. No output 3. compile time 4. c=1

 The answer is option(4).

Explanation:In the above program logical OR operator takes place.Here a!=5 is true which return 1 and rest of the code will not going to be execute because in logical OR if the first condition is true then the rest code will be not execute.