fig03_12.cpp

来自「经典vc教程的例子程序」· C++ 代码 · 共 67 行

// Fig. 3.12: fig03_12.cpp
// A scoping example
#include <iostream.h>

void a( void );   // function prototype
void b( void );   // function prototype
void c( void );   // function prototype

int x = 1;      // global variable

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

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

   {            // start new scope
      int x = 7;

      cout << "local x in inner scope of main is " << x << endl;
   }            // end new scope

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

   a();         // a has automatic local x
   b();         // b has static local x
   c();         // c uses global x
   a();         // a reinitializes automatic local x
   b();         // static local x retains its previous value
   c();         // global x also retains its value

   cout << "local x in main is " << x << endl;

   return 0;
}

void a( void )
{
   int x = 25;  // initialized each time a is called

   cout << endl << "local x in a is " << x 
        << " after entering a" << endl;
   ++x;
   cout << "local x in a is " << x 
        << " before exiting a" << endl;
}

void b( void )
{
    static int x = 50;  // Static initialization only
                        // first time b is called.
    cout << endl << "local static x is " << x 
         << " on entering b" << endl;
    ++x;
    cout << "local static x is " << x 
         << " on exiting b" << endl;
}

void c( void )
{
   cout << endl << "global x is " << x 
        << " on entering c" << endl;
   x *= 10;
   cout << "global x is " << x << " on exiting c" << endl;
}