Difference between procedures and functions in C++

In very simple terms in C++ a procedure is a function with return type as void.

Generally speaking we use the term procedure to refer to a routine, like the ones above, that simply carries out some task (in C++ its definition begins with void). A function is like a procedure but it returns a value; its definition begins with a type name, e.g. int or double indicating the type of value it returns. Procedure calls are statements that get executed, whereas function calls are expressions that get evaluated.

A simple program to show the difference as follows:

//Program tested on Microsoft Visual Studio 2008 - Zahid Ghadialy
//This program shows difference between functions and procedures
#include<iostream>

using namespace std;

//function
bool checkIfPositive(int x)
{
  if(x >= 0)
    return true;
  return false;
}

//procedure
void printIfPositive(int x)
{
  bool isPositive = checkIfPositive(x);
  if(isPositive)
    cout<<"x is positive and its value is "<<x<<endl;
}

int main()
{
  printIfPositive(3);
  printIfPositive(-54);
  printIfPositive(710);
  return 0;
}

The output is as follows: