control reaches end of non-void function(c++)

Question

I have this modefied binary search function that finds the lowest( the value that is closest to L - a known value) and the highest value in a vector(the value that is closest to R - the same known value). Unfortunatelty, when I try to compile the code I get this warning and I dont know why: control reaches end of non-void function.

int bs_counts (vector <int> Arr, int x, int low, int high, bool searchDirection)
 {
     bool done = false;
     int new_middle = 0;
      int mid = (low + high)/2;
     
     while(low <= high && done == true)
     {
         if(Arr[mid] == x)
         {
             new_middle = mid;
             done = true;
         }
         else if(Arr[mid] > x)
         {
             high = mid - 1;
         }
         else
         {
             low = mid + 1;
         }
     }
        if(done == true)
        {
            return new_middle;
        }
        else
        {
            if(searchDirection == true)
            {
                return low;
            }
            else if (searchDirection == false)
            {
                return high;
            }
        }
 }

Answer 1

1st of all, please format your code properly, as it looks like the 3 return statements are inside the while loop, which isn't the case.

The compiler is confused, look at this fragment of code.

if (done == true)
{
    return new_middle;
}
else
{
    if (searchDirection == true)
    {
        return low;
    }
    else if (searchDirection == false)
    {
        return high;
    }
}

We can obviously see that searchDirection will be either true or false, and something will always be returned, but the compiler might be overlooking that, change it to the following.

if (done == true)
{
    return new_middle;
}
else
{
    if (searchDirection == true)
    {
        return low;
    }
    else
    {
        return high;
    }
}

And the warning disappeared.