fig24_02.cpp

是有关C++编程原理教程的例子程序,全,应该对大家有所帮助

// Fig. 24.2: Fig24_02.cpp
// Demonstrating namespaces.
#include <iostream>
using namespace std; // use std namespace            

int integer1 = 98; // global variable

// create namespace Example                           
namespace Example                                     
{                                                     
   // declare two constants and one variable          
   const double PI = 3.14159;                         
   const double E = 2.71828;                          
   int integer1 = 8;                                  
                                                      
   void printValues(); // prototype                   
                                                      
   // nested namespace                                
   namespace Inner                                    
   {                                                  
      // define enumeration                           
      enum Years { FISCAL1 = 1990, FISCAL2, FISCAL3 };
   } // end Inner namespace                           
} // end Example namespace                            

// create unnamed namespace                           
namespace                                             
{                                                     
   double doubleInUnnamed = 88.22; // declare variable
} // end unnamed namespace                            

int main()
{
   // output value doubleInUnnamed of unnamed namespace
   cout << "doubleInUnnamed = " << doubleInUnnamed;

   // output global variable
   cout << "\n(global) integer1 = " << integer1;

   // output values of Example namespace
   cout << "\nPI = " << Example::PI << "\nE = " << Example::E 
      << "\ninteger1 = " << Example::integer1 << "\nFISCAL3 = "
      << Example::Inner::FISCAL3 << endl;

   Example::printValues(); // invoke printValues function
   return 0;
} // end main

// display variable and constant values
void Example::printValues() 
{
   cout << "\nIn printValues:\ninteger1 = " << integer1 << "\nPI = " 
      << PI << "\nE = " << E << "\ndoubleInUnnamed = " 
      << doubleInUnnamed << "\n(global) integer1 = " << ::integer1 
      << "\nFISCAL3 = " << Inner::FISCAL3 << endl;
} // end printValues

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