黑马程序员---Objective-C基础学习---一道课后习题引发的思考

 1 #import <Foundation/Foundation.h>
 2 #import <math.h>
 3  
 4 @interface Point2D : NSObject
 5  
 6 // 点
 7 {
 8     double _x; // x的值
 9     double _y; // y的值
10 }
11  
12 // x的get和set方法
13  
14 - (void)setX : (double)x;
15 - (double)x;
16  
17 // y的get和set方法
18 - (void)setY : (double)y;
19 - (double)y;
20  
21 // 同时设置x和y的值
22 - (void)setX : (double)x andY : (double)y;
23  
24 // 计算和其他点得距离
25 - (double)distanceWithOtherPoint : (Point2D *)p;
26  
27 // 计算点和点之间的距离
28 + (double)distanceBetweenPoint1 : (Point2D *)p1 andPoint2 : (Point2D *)p2;
29  
30 @end // Point2D声明
31  
32 // 方法
33 @implementation Point2D
34  
35 - (void)setX : (double)x
36 {
37     _x = x;
38 }
39 - (double)x
40 {
41     return _x;
42 }
43 - (void)setY : (double)y
44 {
45     _y = y;
46 }
47 - (double)y
48 {
49     return _y;
50 }
51 - (void)setX : (double)x andY : (double)y
52 {
53     _x = x;
54     _y = y;
55    
56      // [self setX:x]; //设置x过程中可能涉及到过滤的问题，如果x的值不符合要求，我们需要处理
57     // [self setY:y];
58      
59 }
60 - (double)distanceWithOtherPoint : (Point2D *)p
61 {   
62     double x1 = [p x];
63     double y1 = [p y];
64     return  sqrt(pow(_x-x1, 2) + pow(_y-y1, 2));
65 }
66 + (double)distanceBetweenPoint1 : (Point2D *)p1 andPoint2 : (Point2D *)p2
67 {
68     double x1 = [p1 x];
69     double y1 = [p1 y];
70     double x2 = [p2 x];
71     double y2 = [p2 x];
72     return sqrt(pow(x1-x2, 2) + pow(y1-y2, 2));
73 }
74  
75 @end //Point2D
76  
77 //主函数
78 int main()
79 {
80     Point2D *pt1 = [Point2D new];
81     Point2D *pt2 = [Point2D new];
82     Point2D *pt3 = [Point2D new];
83     //[pt1 setX : 2 andY : 2];
84     [pt2 setX : 4 andY : 4];   
85     [pt3 setX : 9 andY : 9];
86     double distance1 = [pt1distanceWithOtherPoint : pt2];
87     double distance2 = [Point2DdistanceBetweenPoint1 : pt2 andPoint2 : pt3];
88     NSLog(@"The distande with other point is %f",distance1);
89     NSLog(@"The distande between point1 and point2 is %f",distance2);
90    
91     return 0;
92    
93 }

1 - (double)distanceWithOtherPoint : (Point2D *)p
2 {   
3     double x1 = [p x];
4     double y1 = [p y];
5     return  sqrt(pow(_x-x1, 2) + pow(_y-y1,2));
6 }

1 - (double)distanceWithOther:(Point2D *)other
2 {
3     // 不要再傻乎乎算一遍了，直接调用类方法即可
4     return [Point2DdistanceBetweenPoint1:self andPoint2:other];
5 }

1 + (double)distanceBetweenPoint1 : (Point2D *)p1 andPoint2 : (Point2D *)p2
2 {
3     double x1 = [p1 x];
4     double y1 = [p1 y];
5     double x2 = [p2 x];
6     double y2 = [p2 x];
7     returnsqrt(pow(x1-x2, 2) + pow(y1-y2, 2));  // 一行代码解决，但可读性不强
8 //
9 }

 1 + (double)distanceBetweenPoint1:(Point2D *)p1 andPoint2:(Point2D *)p2
 2 {
 3     // 两点距离公式：( (x1-x2)的平方 + (y1-y2)的平方 )开根
 4     // x1-x2
 5     double xDelta = [p1 x] - [p2x];
 6     // (x1-x2)的平方
 7     double xDeltaPingFang =pow(xDelta, 2);
 8     // y1-y2
 9     double yDelta = [p1 y] - [p2y];
10     // (y1-y2)的平方
11     double yDeltaPingFang =pow(yDelta, 2);
12     return sqrt(xDeltaPingFang + yDeltaPingFang);
13 }

 1 - (void)setX : (double)x andY : (double)y
 2 {
 3     _x = x;
 4     _y = y;
 5 }  // 这里没考虑到设置x过程中可能涉及到过滤的问题，如果x的值不符合要求，我们需要处理
 6  
 7 // 方法二
 8 - (void)setX : (double)x andY : (double)y
 9 {
10     [self setX:x];  // 这里调用set方法设置x和y的值,考虑了x过滤问题
11     [self setY:y];
12 }