Variables, revisited

It's always nice to revisit a topic you've covered before, now that you understand C++ coding much more in depth.

Global variables

Now that we've introduced the concept of functions, the concept of a global variable can be introduced.

What is a global variable? A global variable is any variable that is made accessible to all the functions of the program. How can we make a variable that is accessible to all the functions of the program? We simply declare the global variable at the top of the code file, usually after or near the #include statements.

Here's an example program with some global variables:

#include <iostream>
#include <string>
using namespace std;

string g_string;	// global string variable,
// accessible to all functions within the program
// (because it is declared before any of the functions
// below!)

void addA(){ g_string += "A"; }
void addB(){ g_string += "B"; }
void addC(){ g_string += "C";...