#include <iostream>

 /* run this program using the console pauser or add your own getch, system("pause") or input loop */

 using namespace std;

 //声明全局变量并初始化

 extern int a[]={,,};

 extern float p=3.14;

 //在show()函数中使用外部变量

 show()  {

     int i;

     cout<<"In show():"<<endl;

     cout<<"p="<<p<<endl;

     cout<<"a[]: ";

     for (i=;i<=;i++)

         cout<<a[i]<<"  ";

     cout<<endl;

     //cout<<"y="<<y<<endl; 编译出错！

 }

 //声明外部变量并初始化

 int y=;

 int main(int argc, char** argv) {

         //声明局部变量

     int i,p=;

     //显示重名变量

     cout<<"In main():"<<endl;

     cout<<"p="<<p<<endl;

     //显示全局变量

     cout<<"::p="<<::p<<endl;

     cout<<"a[]: ";

     for (i=;i<=;i++)

         cout<<a[i]<<"  ";

     cout<<endl;

     cout<<"y="<<y<<endl;   //编译正确！

     show();  //调用函数

     return ;

 }