Predict the output of below C programs.
Question 1
C
#include<stdio.h>
int main(void)
{
int a = 1;
int b = 0;
b = ++a + ++a;
printf("%d %d",a,b);
getchar();
return 0;
}
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Output: 3 6
Explanation: ++ has precedence over + and operates right to left. Hence rightmost ++a gives a=2 and the ++a left of it gives a=3. Now, while evaluating, b=3+3. As after the second ++a, we have a=3. Hence b=3+3=6 and a=3. Hence the output.
Question 2
C
#include<stdio.h>
int main()
{
int a[] = {1, 2, 3, 4, 5, 6};
int *ptr = (int*)(&a+1);
printf("%d ", *(ptr-1) );
getchar();
return 0;
}
|
Output: 6
&a is address of the whole array a[]. If we add 1 to &a, we get “base address of a[] + sizeof(a)”. And this value is typecasted to int *. So ptr – 1 points to last element of a[]
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