[已解决]C++静态方法

xiannv2b

getcount方法输出的永远是1，即使把return count改成return 0也一样
经测试，把getcount方法改成count属性，会得到想要的

1. 
   
2. #include <iostream>
   
3. 
   
4. class Dog
   
5. {
   
6. public:
   
7.     Dog();
   
8.     ~Dog();
   
9.     int getcount();
   
10. 
    
11. private:
    
12.     static int count;
    
13. };
    
14. 
    
15. int Dog::count = 0;
    
16. 
    
17. Dog::Dog()
    
18. {
    
19.     count += 1;
    
20.     std::cout << "add" << '\n';
    
21. }
    
22. 
    
23. Dog::~Dog()
    
24. {
    
25.     count -= 1;
    
26.     std::cout << "subtract" << '\n';
    
27. }
    
28. 
    
29. int Dog::getcount()
    
30. {
    
31.     return count;
    
32. }
    
33. 
    
34. int main()
    
35. {
    
36.     std::cout << Dog::getcount << '\n';
    
37.     Dog dog1; Dog dog2;
    
38.     std::cout << "count = " << Dog::getcount << '\n';
    
39.     {
    
40.         Dog dog3;
    
41.         std::cout << "count = " << Dog::getcount << '\n';
    
42.     }
    
43.     std::cout << "count = " << Dog::getcount << '\n';
    
44. }
    

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结果

最佳答案

月排行榜 / 总排行榜

jhanker

2022-4-24 09:39:17

改成下面这样就可以了！

1. 
   
2. #include <iostream>
   
3. 
   
4. class Dog
   
5. {
   
6. public:
   
7.     Dog();
   
8.     ~Dog();
   
9. static int getcount();//此处加上 static
   
10. private:
    
11.    static int count;
    
12. };
    
13. 
    
14. int Dog::count = 0;
    
15. 
    
16. Dog::Dog()
    
17. {
    
18.     count += 1;
    
19.     std::cout << "add" << '\n';
    
20. }
    
21. 
    
22. Dog::~Dog()
    
23. {
    
24.     count -= 1;
    
25.     std::cout << "subtract" << '\n';
    
26. }
    
27. 
    
28. int Dog::getcount()
    
29. {
    
30.     return count;
    
31. }
    
32. 
    
33. int main()
    
34. {
    
35.     std::cout <<"Dog::getcount"  << '\n';
    
36.    Dog dog1; Dog dog2;
    
37.     std::cout << "count = " << Dog::getcount() << '\n';//加上()，原先函数调用少了()
    
38.     {
    
39.         Dog dog3;
    
40.         std::cout << "count = " << Dog::getcount() << '\n';//加上()，原先函数调用少了()
    
41.     }
    
42.     std::cout << "count = " << Dog::getcount() << '\n';//加上()，原先函数调用少了()
    
43.         return 0;
    
44. }

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jhanker

改成下面这样就可以了！

1. 
   
2. #include <iostream>
   
3. 
   
4. class Dog
   
5. {
   
6. public:
   
7.     Dog();
   
8.     ~Dog();
   
9. static int getcount();//此处加上 static
   
10. private:
    
11.    static int count;
    
12. };
    
13. 
    
14. int Dog::count = 0;
    
15. 
    
16. Dog::Dog()
    
17. {
    
18.     count += 1;
    
19.     std::cout << "add" << '\n';
    
20. }
    
21. 
    
22. Dog::~Dog()
    
23. {
    
24.     count -= 1;
    
25.     std::cout << "subtract" << '\n';
    
26. }
    
27. 
    
28. int Dog::getcount()
    
29. {
    
30.     return count;
    
31. }
    
32. 
    
33. int main()
    
34. {
    
35.     std::cout <<"Dog::getcount"  << '\n';
    
36.    Dog dog1; Dog dog2;
    
37.     std::cout << "count = " << Dog::getcount() << '\n';//加上()，原先函数调用少了()
    
38.     {
    
39.         Dog dog3;
    
40.         std::cout << "count = " << Dog::getcount() << '\n';//加上()，原先函数调用少了()
    
41.     }
    
42.     std::cout << "count = " << Dog::getcount() << '\n';//加上()，原先函数调用少了()
    
43.         return 0;
    
44. }

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jhanker

std::cout << Dog::getcount << '\n';
std::cout << "count = " << Dog::getcount << '\n';
  std::cout << "count = " << Dog::getcount << '\n';
  std::cout << "count = " << Dog::getcount << '\n';
这几句代码都是有问题的。对于类本身无法调用getcount ()函数