Please help with my code.

Ok, I have to write a function called distance that will calculate the distance between 2 points in an x-y coordinate system. Each point will be specified by 2 double values. Also, this function will not contain any input/output code (i.e. no printf or scanf function calls).

Write a complete program that will test your function.

How am I supposed to test my results, if I can't have no input/output code? Please help me.

This is my code, but I haven't finished it yet, because I don't know what to do after that. Please help.

Code:

#include <stdio.h>
#include <math.h>
 
using namespace std;
 
double distance(double xOne, double yOne, double xTwo, double yTwo)
            {
                  double xS, yS, result;
                  xS= xTwo - xOne;
                  xS= xS*xS;  // value of x squared under radical
                  yS = yTwo - yOne;
                  yS = yS*yS;  //value of y squared under radical
 
                  result = sqrt(xS + yS);
                  return result;
            }

It says the FUNCTION cannot contain any input/output. I'm sure you can use it outside the function.

Code:

using namespace std;

This isn't C