‘，’之后要留空格，如 Function(x, y, z)

 1 #include <iostream>
 2 
 3 /* run this program using the console pauser or add your own getch, system("pause") or input loop */
 4 using namespace std;
 5 //声明全局变量并初始化
 6 extern int a[]={1,2,3};
 7 extern float p=3.14;
 8 
 9 //在show()函数中使用外部变量
10 show()  {
11     int i;
12     cout<<"In show():"<<endl;
13     cout<<"p="<<p<<endl;
14     cout<<"a[]: ";
15     for (i=0;i<=2;i++) 
16         cout<<a[i]<<"  ";
17     cout<<endl;
18     //cout<<"y="<<y<<endl; 编译出错！
19 }
20 
21 //声明外部变量并初始化
22 int y=5678;
23 
24 int main(int argc, char** argv) {
25     
26         //声明局部变量
27     int i,p=100;
28 
29     //显示重名变量
30     cout<<"In main():"<<endl;
31     cout<<"p="<<p<<endl;
32 
33     //显示全局变量
34     cout<<"::p="<<::p<<endl;
35     cout<<"a[]: ";
36     for (i=0;i<=2;i++)
37         cout<<a[i]<<"  ";
38     cout<<endl;
39     cout<<"y="<<y<<endl;   //编译正确！
40 
41     show();  //调用函数
42     return 0;
43 }