Predict the output of below C programs.
Question 1
#include<stdio.h>
int main()
{
int a;
char *x;
x = (char *) &a;
a = 512;
x[0] = 1;
x[1] = 2;
printf("%d\n",a);
getchar();
return 0;
}
Answer: The output is dependent on endianness of a machine. Output is 513 in a little endian machine and 258 in a big endian machine.
Let integers are stored using 16 bits. In a little endian machine, when we do x[0] = 1 and x[1] = 2, the number a is changed to 00000001 00000010 which is representation of 513 in a little endian machine. The output would be same for 32 bit numbers also.
In a big endian machine, when we do x[0] = 1 and x[1] = 2, the number is changed to 00000001 00000010 which is representation of 258 in a big endian machine.
Question 2
int main()
{
int f = 0, g = 1;
int i;
for(i = 0; i < 15; i++)
{
printf("%d \n", f);
f = f + g;
g = f - g;
}
getchar();
return 0;
}
Answer: The function prints first 15 Fibonacci Numbers.
Question 3
Explain functionality of following function.
int func(int i)
{
if(i%2) return (i++);
else return func(func(i-1));
}
Answer: If n is odd then returns n, else returns (n-1). So if n is 12 then we get 11 and if n is 11 then we get 11.
Please write comments if you find any of the answers/explanations incorrect, or you want to share more information about the topics discussed above.
