/*
    testfunc07.cpp
    CIS 150
    2008-06-10
    David Klick
   
    This program demonstrates variable scope.
*/

#include <iostream>
using std::cin;
using std::cout;

void changeXYZ(int n); // function prototype 
void cont();

int w = 3;            // global variable
int y = 5;            // global variable

int main(int argc, char* argv[]) {
    int x = 7;  // seen only within main
    int y = 9;  // seen only within main; hides global y
    int z = 11; // seen only within main

    // see what values are before function call
    cout << "Before calling changeXYZ: w=" << w
         << ", x=" << x << ", y=" << y << ", z="
         << z << '\n';

    changeXYZ(z);  // try to change values
   
    // see what values are after function call
    cout << "After calling changeXYZ:  w=" << w
         << ", x=" << x << ", y=" << y << ", z="
         << z << '\n';

    cont();
    return 0;
}

/*
    void changeXYZ(int z);
   
    Arguments:
        int z: an arbitrary integer value
   
    Returns: nothing

    Try to change x, y, and z values. Variables x, y, and
    z are all local to calling function. Variable x is local
    to this function. Variable z's value is passed in as
    an argument. Variable y is also globally declared.
*/
void changeXYZ(int z) {
    int x = 2;  // must declare since main's x can't be seen here
    y = 4;      // changes global y
    z = 6;      // tries to change value of z
    cout << "Inside changeXYZ:         w=" << w
         << ", x=" << x << ", y=" << y << ", z="
         << z << '\n';
}

/*
    void cont();
   
    Arguments: none
   
    Returns: nothing
   
    Clears input buffer and pauses waiting for user 
    to press Enter.
*/
void cont() {
    if (cin.rdbuf()->sungetc() != -1 && cin.get() != '\n') cin.ignore(80,'\n');
    cout << "Press enter to continue...";
    cin.get();
}

/*
    Sample output:
   
    Before calling changeXYZ: w=3, x=7, y=9, z=11
    Inside changeXYZ:         w=3, x=2, y=4, z=6
    After calling changeXYZ:  w=3, x=7, y=9, z=11
*/