inline 内联函数可以避免函数重定义问题

在.h中定义了和main函数中一样的函数,在返回值前面添加修饰关键字inline即可.

.h中的生命和.cpp中的实现

 1 #if !defined(AFX_STDAFX_H__CF8E6B35_199B_45D0_9F2A_929A26911DD2__INCLUDED_)
 2 #define AFX_STDAFX_H__CF8E6B35_199B_45D0_9F2A_929A26911DD2__INCLUDED_
 3 
 4 #if _MSC_VER > 1000
 5 #pragma once
 6 #endif // _MSC_VER > 1000
 7 
 8 #define WIN32_LEAN_AND_MEAN        // Exclude rarely-used stuff from Windows headers
 9 
10 #include 
11 
12 
13 inline void Fun();
14 
15 
16 // TODO: reference additional headers your program requires here
17 
18 //{{AFX_INSERT_LOCATION}}
19 // Microsoft Visual C++ will insert additional declarations immediately before the previous line.
20 
21 #endif // !defined(AFX_STDAFX_H__CF8E6B35_199B_45D0_9F2A_929A26911DD2__INCLUDED_)

 1 #include "stdafx.h"
 2 #include 
 3 
 4 // TODO: reference any additional headers you need in STDAFX.H
 5 // and not in this file
 6 
 7 inline void Fun()
 8 {
 9   cout << " .h Fun()" << endl;
10 }

 

main中的函数inline void Fun();

 1 #include "stdafx.h"
 2 #include <string.h>
 3 #include 
 4 #include 
 5 
 6 
 7 // inline void Fun();
 8 
 9 inline void Fun()
10 {
11   cout << "Main() Fun()" << endl;
12 }
13 
14 void Fun2(int nData = 2)
15 {
16   
17 }
18 
19 
20 int main(int argc, char* argv[])
21 {
22 
23   void Fun3(int&);
24 
25   Fun();
26   Fun2(3);
27 
28   int nData = 4;
29 
30   Fun3(nData);
31   
32   cout << nData << endl;
33   
34   return 0;
35 }
36 
37 void Fun3(int& nData )
38 {
39   nData = 90;
40  // cout << nData << endl; 
41 }

Fun3(int&);函数调用的时候引用,在函数中更改了数值之后,穿进去的变量的值也会更改.