Find sum of elements in the array

Question

I have this program which worked find in my college lab, but when I run it at my home it gives different result

#include <stdio.h>
int main(int argc, char* argv[]) {
        const int size=100;
        int n, sum=0;
        int* A = (int*)malloc( sizeof(int)*size );
        for (n=size-1; n>0; n--)
                A[n] = n;

        for (n=0;n<size; n++)
                sum += A[n];

        printf ("sum=%d\n", sum);
        return 0;

}

I'm expecting 4950 as result but I keep getting different result like 112133223. Why is this happening ?

Answer 1

You are not assigning value to A[0]. As a result of this A[0] will have garbage value which is getting added to sum.

Change

for (n=size-1; n>0; n--)
               ^^^

to

for (n=size-1; n>=0; n--)
               ^^^^

Also you need to free the dynamically allocated memory by doing:

free(A);

before you return.