Introduction to subprograms - c++

Question

Trying to fulfill the coding prompt
Input a list of positive numbers, find the mean (average) of the numbers, and output the result. Use a subprogram to input the numbers, a function to find the mean, and a subprogram to output the result.
I have done smaller calls with passing arguments but this one requires 3 separate subprograms, 1 for input, 1 for calculations and one to display the result.
So far my program is does not start the initial call for input
#include <iostream>
using namespace std;
//prototypes
int prompt(int sum, int count );
float average(int sum, int count);
void result(float avg);
int main()
{
int num;
cout << "Welcome to Keith's Averaging program";
cout << endl;
int prompt();
int average (int sum, int count);
void result (float avg);
return 0;
}
//Prototype Definitions
//get numbers from users
int prompt()
{
int num, sum, count;
cout << "Enter numbers and I will Average them." << endl;
cout << "Please enter a number: ";
cin >> num;
sum = sum + num;
if(num == 0)
{
cout << "Guess you don't want an average";
cout << endl;
cout << "Goodbye";
}
for(count=0; num !=0; count++)
{
cout << "Please enter a positive number, enter zero to compute the avg: ";
cin >> num;
if(num < 0)
{
cout << "Enter a positive number:";
cin >> num;
}
sum = sum + num;
}
Displays my welcome message then exits

Answer 1

I have put some comments in your code as explanation.
#include <iostream>
using namespace std;
//prototypes // These are declarations, definitions should also contain
// same function signatures
int prompt(int& sum, int& count); // accept arguments as reference (Read about it)
float average(int& sum, int& count);
void result(float& avg);
int main()
{
// int num; // don't need num in this function, not used
int sum = 0, count = 0; // create variables sum and count and initialize them to 0
float avg;
cout << "Welcome to Keith's Averaging program";
cout << endl;
prompt(sum, count); // don't need function return type and argument return type when calling
// a function
cout << sum << " " << count << endl; // print the values after prompt() call
// prompt() call must have filled the values sum and count
average(sum, count);
result(avg);
return 0;
}
//Prototype Definitions
//get numbers from users
int prompt(int& sum, int& count)
{
int num;
cout << "Enter numbers and I will Average them." << endl;
cout << "Please enter a number: ";
cin >> num;
sum = sum + num;
if(num == 0)
{
cout << "Guess you don't want an average";
cout << endl;
cout << "Goodbye";
}
for(count=0; num !=0; count++)
{
cout << "Please enter a positive number, enter zero to compute the avg: ";
cin >> num;
if(num < 0)
{
cout << "Enter a positive number:";
cin >> num;
}
sum = sum + num;
}
}
float average(int& sum, int& count){
// TODO: implement this
}
void result(float& avg) {
// TODO: implement this
}
I have changed various parts of your code. I changed the function prototypes so that they take arguments by reference.
In the int main() function, I created two variables sum and count and initialized them to 0 - we will use these variables when calling those functions.
In the int prompt() function, I changed the function signature so that it matches the declared definition (otherwise it would have been some other function). Also, I removed the local declarations sum and count since we now have them as function arguments.
I have also put the definition blocks for other two functions and you can implement them (I have marked them as // TODO).