Run-Time Check Failure #2 - Stack around the variable 'k' was corrupted

Question

an exercise:find out the perfect number from 1 to 1000 (perfect number:such as 6,because 6=1+2+3) this is my code.

#include<iostream>
using namespace std;
int main()
{
    int k[11];
    int i, a, n, s;
    for (a = 2; a <= 1000; a++)
    {
        n = 0;
        s = a;
        for (i = 1; i < a; i++)
            if (a%i == 0)
            {
                n++;
                s = s - i;
                k[n] = i;
            }
        if (s == 0)
        {
            cout << a << " is a perfect number" << endl;
            cout << "its factors are:";
            for (i = 1; i <= n; i++)cout << k[i] << " ";
            cout <<  endl;
        }
    }
    return 0;
}

but it shows Run-Time Check Failure #2 - Stack around the variable 'k' was corrupted when I change int k[11] to int k[32] it is correct.

the array element is at least 32 ,so why?

Answer 1

Array indices start at 0. You are incrementing n too early. And obviously, 10 is too small as the array size. What formula gives this size?