position.cpp

int position(int key, int elemArray[]) {

    int bottom = 0;
    int top = elemArray.length - 1;
    while (bottom <= top) {
    
        int midpoint = (top + bottom) / 2;

        // found it
        if (key == elemArray[midpoint])
            return midpoint;

        // top half
        if (key < elemArray[midpoint])
            bottom = midpoint + 1;

        // bottom half
        else
            top = midpoint - 1;
    }

    // not in the array
    return -1;
}

position.hpp

int position(int key, int elemArray[]);

sort.hpp

void sort(double n[], int size);