// Scope example

// Based on Kurt McMahon's example, originally from Deitel & Deitel, 
// _C++: How to Program_, 4e


#include <iostream>

using std::cout;
using std::endl;

void useLocal();        // function prototype
void useStaticLocal();  // function prototype
void useGlobal();       // function prototype

int x = 1;      // global variable

int main()
{
  int x = 5;   // local variable to main

  cout << "local x in main's outer scope is " << x << endl;

  { // start new scope
     
    int x = 7;

    cout << "local x in main's inner scope is " << x << endl;

  } // end new scope

  cout << "local x in main's outer scope is " << x << endl;

  useLocal();       // useLocal has local x
  useStaticLocal(); // useStaticLocal has static local x
  useGlobal();      // useGlobal uses global x
  useLocal();       // useLocal reinitializes its local x
  useStaticLocal(); // static local x retains its prior value
  useGlobal();      // global x also retains its value

  cout << "\nlocal x in main is " << x << endl;

  return 0;  // indicates successful termination

} // end main


// useLocal reinitializes local variable x during each call
void useLocal()
{
  int x = 25;  // initialized each time useLocal is called

  cout << endl << "local x is " << x 
       << " on entering useLocal" << endl;

  cout << "local x (prefix increment) is " << ++x << endl;
  cout << "local x (after prefix increment) is " << x << endl;
  cout << "local x (postfix increment) is " << x++ << endl;
  cout << "local x (after postfix increment) is " << x << endl; 

  cout << "local x is " << x 
       << " on exiting useLocal" << endl;

} // end function useLocal


// useStaticLocal initializes static local variable x only the
// first time the function is called; value of x is saved
// between calls to this function
void useStaticLocal()
{
  // initialized first time useStaticLocal is called.
  static int x = 50;  

  cout << endl << "local static x is " << x 
       << " on entering useStaticLocal" << endl;
  x++; 
  cout << "local static x is " << x 
       << " on exiting useStaticLocal" << endl;

} // end function useStaticLocal


// useGlobal modifies global variable x during each call
void useGlobal( void )
{
  cout << endl << "global x is " << x 
       << " on entering useGlobal" << endl;
  x *= 10;
  cout << "global x is " << x 
       << " on exiting useGlobal" << endl;
   
} // end function useGlobal