1. /*
   
2. 设计一个方法，用来和其他车比较车速，返回车速的差距
   
3. */
   
4. 
   
5. #import <Foundation/Foundation.h>
   
6. 
   
7. @interface Car : NSObject
   
8. {
   
9.     @public
   
10.     int speed;
    
11. }
    
12. 
    
13. - (int)compareSpeedWithOther:(Car *)other;
    
14. 
    
15. @end
    
16. 
    
17. @implementation Car
    
18. 
    
19. - (int)compareSpeedWithOther:(Car *)other
    
20. {
    
21.     // speed
    
22.     // other->speed
    
23.     // 返回当前这辆车和other这辆车的速度差距
    
24.     return speed - other->speed;
    
25. }
    
26. 
    
27. @end
    
28. 
    
29. int main()
    
30. {
    
31.     Car *c1 = [Car new];
    
32.     c1->speed = 300;
    
33.    
    
34.     Car *c2 = [Car new];
    
35.     c2->speed = 250;
    
36.    
    
37.     int a = [c1 compareSpeedWithOther:c2];
    
38.    
    
39.     NSLog(@"a=%d", a);
    
40.    
    
41.     return 0;
    
42. }

复制代码

int a = [c1 compareSpeedWithOther:c2]   主要就是这一句用内存怎么表示