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Introducing the Global Reach

Program

The Global Reach program demonstrates global variables. The program shows how you can access a global variable from anywhere in your program. It also shows how you can hide a global variable in a scope. Finally, it shows that you can change a global variable from anywhere in your program. Figure 5.4 shows the results of the program.

You can download the code for this program from the Course Technology website (www.courseptr.com/downloads). The program is in the Chapter 5 folder; the filename is global_reach.cpp.

// Global Reach

// Demonstrates global variables #include <iostream>

Using Global Variables 167


image

Figure 5.4

You can access and change global variables from anywhere in a program—but they can also be hidden in a scope as well.


using namespace std;

int glob = 10; // global variable void access_global();

void hide_global(); void change_global();


int main()

{

cout << "In main() glob is: " << glob << "\n\n"; access_global();


hide_global();

cout << "In main() glob is: " << glob << "\n\n";


change_global();

cout << "In main() glob is: " << glob << "\n\n";


return 0;

}

168 Chapter 5 n Functions: Mad Lib


void access_global()

{

cout << "In access_global() glob is: " << glob << "\n\n";

}


void hide_global()

{

int glob = 0; // hide global variable glob

cout << "In hide_global() glob is: " << glob << "\n\n";

}


void change_global()

{

glob = -10; // change global variable glob

cout << "In change_global() glob is: " << glob << "\n\n";

}