分开放在几个文件里面就连接通不过了？？

pupilzeng

1. 
   
2. //mydate.h
   
3. #ifndef MYDATE_H
   
4. #define MYDATE_H
   
5. 
   
6. #include<iostream>
   
7. 
   
8. 
   
9. class mydate{
   
10. public:
    
11.         mydate( short unsigned = 1900, short unsigned = 1, short unsigned = 1 );
    
12.         short unsigned gety() const;
    
13.         short unsigned getm() const;
    
14.         short unsigned getd() const;
    
15. 
    
16. private:
    
17.         short unsigned year, month, day;
    
18. };
    
19. 
    
20. #endif //MYDATE_H
    
21. 
    
22. //mydate.cpp
    
23. #include"mydate.h"
    
24. #include<iostream>
    
25. #include<iomanip>
    
26. 
    
27. mydate::mydate( short unsigned y , short unsigned m , short unsigned d )
    
28. {
    
29.         year = y;
    
30.         month = m;
    
31.         day = d;
    
32. }
    
33. 
    
34. 
    
35. inline short unsigned mydate::gety() const
    
36. { return year; }
    
37. 
    
38. inline short unsigned mydate::getm() const
    
39. { return month; }
    
40. 
    
41. inline short unsigned mydate::getd() const
    
42. { return day; }
    
43. 
    
44. //main.cpp
    
45. #include"mydate.h"
    
46. #include<iostream>
    
47. using namespace std;
    
48. 
    
49. 
    
50. int main()
    
51. {
    
52.         mydate md( 2003, 7, 21 );
    
53.         cout << md.gety() << endl;
    
54. }
    
55. 
    

复制代码

>g++ -o main mydate.cpp main.cpp
/tmp/cclXKKOO.o(.text+0x38): In function `main':
: undefined reference to `mydate::gety() const'
collect2: ld returned 1 exit status

如果写在一个文件里面：

1. 
   
2. //main.cpp
   
3. #include<iostream>
   
4. using namespace std;
   
5. 
   
6. 
   
7. class mydate{
   
8. public:
   
9.         mydate( short unsigned  = 1900, short unsigned  = 1, short unsigned  = 1 );
   
10.         short unsigned gety() const;
    
11.         short unsigned getm() const;
    
12.         short unsigned getd() const;
    
13. 
    
14. private:
    
15.         short unsigned year, month, day;
    
16. };
    
17. 
    
18. int main()
    
19. {
    
20.         mydate md(2003, 7, 21 );
    
21.         cout << md.gety() << endl;
    
22. }
    
23. mydate::mydate( short unsigned y , short unsigned m , short unsigned d )
    
24. {
    
25.         year = y;
    
26.         month = m;
    
27.         day = d;
    
28. }
    
29. 
    
30. 
    
31. inline short unsigned mydate::gety() const
    
32. { return year; }
    
33. 
    
34. inline short unsigned mydate::getm() const
    
35. { return month; }
    
36. 
    
37. inline short unsigned mydate::getd() const
    
38. { return day; }
    

复制代码

>g++ -o main main.cpp
通过

请问这时什么原因？

libinary

inline函数必须和声明在一个文件里，你可以把inline函数写在.h文件里，不要写在.cpp文件里。

pupilzeng

谢谢
解决了