Why is there an infinite loop in my program?

Question

int main(void)
{
    int i;
    int array[5];

    for (i = 0; i <= 20; i++)
    array[i] = 0;

    return 0;
}

Why is the above code stuck in a

Answer 1

You are invoking undefined behaviour by overwriting beyond the memory you are allowed. So anything can happen.

Most likely, it's overwriting the loop counter.