‘，’之後要留空格，如 Function(x, y, z)。如果‘;’不是一行的結束 符號，其後要留空格，如 for (initialization; condition; update)。

 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 //聲明全局變量並初始化
 6 extern int a[]={1,2,3};
 7
 
 extern float p=3.14;
 8 
 9 //在show()函數中使用外部變量
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; 編譯出錯！
 

19 }
20 
21 //聲明外部變量並初始化
22 int y=5678;
23 
24 int main(int argc, char** argv) {
25     
26         //聲明局部變量
27     int i,p=100;
28 
29     //顯示重名變量
30     cout<<"In main():"<<endl;
31     cout<<"p="<<p<<endl;
32 
33     //顯示全局變量
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;   //編譯正確！
40 
41     show();  //調用函數
42     return 0;
43 }

‘，’之後要留空格，如 Function(x, y, z)