PSET3: Search Finds 0 when it doesn't exist in values

Question

I have a file containing sorted numbers 1 to 20, on which I run the search. It finds 0 when it's not in the values. Why is this?

When int end = n; is used, 20 isn't found. However, when I use int end = n + 1;, 20 is found. Why is this?

bool search(int value, int values[], int n)
{
    // TODO: implement a searching algorithm

    int start = 0;
    int end = n + 1;
    int m;
    int i = 0;

    while ( n > i)
    {
        // find middle
        m = start + end;
        m /= 2;

        if (m == value)
        {
            return true;
        }

        // shift middle to right by 1
        else if (value > m)
        {
            start = m++;
        }

        // shift middle to left by 1
        else if (value < m)
        {
            end = m--;
        }

        i++;
    }
    return false;
}

Answer 1

I figured it out. The code was searching if a value exists at index of m. Instead of, if the value exists in m.