Run-Time Check Failure #2 - Stack around the variable 'arr' was corrupted. I tried to find-CodePudding

what was i trying to do is a recursion of first 40 fibonacci numbers, when tried to launch a program, it's stopped at return 0;.

#include <stdio.h>
#define SIZE 40
void sum(int arr[], int n1, int n2, int offset);

int main(void)
{
    int arr[SIZE] = { 0, 1 };

    printf("%d\n", arr[0]);
    printf("%d\n", arr[1]);
    sum(arr, 0, 1, 2);

    return 0;
}
void sum(int arr[], int n1, int n2, int offset)
{
    if (offset > SIZE)
        return;

    arr[offset] = arr[n1]   arr[n2];
    printf("%d\n", arr[offset]);
    sum(arr, n1   1, n2   1, offset   1);
}

CodePudding user response：

Look at this check:

if (offset > SIZE)
    return;

That means if offset is equal to SIZE, it passes.

arr[offset] with offset being equal to SIZE refers to the 41 nth element.

This array only have 40 element, hence the corruption.

If you run your program in a debugger, it should stop at the crash and you would be able to look at the value of offset that caused the crash.

A solution for this would be to change the check to if (offset >= SIZE).