一道Objective-C作业题 - 黑马程序员技术交流社区

#import <Foundation/Foundation.h>
#import <math.h>
// 点
@interface Point2D : NSObject
{
double _x; // x值
double _y; // y值
}
// x值的getter和setter
- (void)setX:(double)x;
- (double)x;
// y值的getter和setter
- (void)setY:(double)y;
- (double)y;
// 同时设置x和y
- (void)setX:(double)x andY:(double)y;
// 计算跟其他点的距离
- (double)distanceWithOther:(Point2D *)other;
// 计算两个点之间的距离
+ (double)distanceBetweenPoint1:(Point2D *)p1 andPoint2:(Point2D *)p2;
@end
@implementation Point2D
// x值的getter和setter
- (void)setX:(double)x
{
_x = x;
}
- (double)x
{
return _x;
}
// y值的getter和setter
- (void)setY:(double)y
{
_y = y;
}
- (double)y
{
return _y;
}
// 同时设置x和y
- (void)setX:(double)x andY:(double)y
{
// 第1种思路
// _x = x;
// _y = y;
// 第2种思路
[self setX:x];
[self setY:y];
}
// 计算跟其他点的距离
- (double)distanceWithOther:(Point2D *)other
{
// 不要再傻乎乎算一遍了，直接调用类方法即可
return [Point2D distanceBetweenPoint1:self andPoint2:other];
}
// 计算两个点之间的距离
+ (double)distanceBetweenPoint1:(Point2D *)p1 andPoint2:(Point2D *)p2
{
// 两点距离公式：( (x1-x2)的平方 + (y1-y2)的平方 )开根
// x1-x2
double xDelta = [p1 x] - [p2 x];
// (x1-x2)的平方
double xDeltaPingFang = pow(xDelta, 2);
// y1-y2
double yDelta = [p1 y] - [p2 y];
// (y1-y2)的平方
double yDeltaPingFang = pow(yDelta, 2);
return sqrt(xDeltaPingFang + yDeltaPingFang);
}
@end
// Circle类继承Point2D
@interface Circle : Point2D
{
double _radius; // 半径
}
// radius值的setter和getter方法
- (void)setRadius:(double)radius;
- (double)radius;

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编译链接发现有3个警告和1个错误：

circle.m:130:15: warning: 'Point2D' may not respond to 'radius'
double r=[c1 radius] + [c2 radius];
^
circle.m:130:29: warning: 'Point2D' may not respond to 'radius'
double r=[c1 radius] + [c2 radius];
^
circle.m:131:16: warning: class method '+diatanceBetweenPoint1:andPoint2:' not
found (return type defaults to 'id')
double dis=[Point2D diatanceBetweenPoint1:c1 andPoint2: c2];
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
circle.m:131:12: error: initializing 'double' with an expression of incompatible
type 'id'
double dis=[Point2D diatanceBetweenPoint1:c1 andPoint2: c2];
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3 warnings and 1 error generated.
zous-Mac:objective-c shao$

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记得老师说过父类不能调用子类独有的方法，这导致了前两个警告，但是后面的警告和错误是怎么回事呢？

//上面代码不完整，这里是我的完整代码

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/**
6.设计一个类Circle，用来表示二维平面中的圆
1> 属性
* double radius （半径）
* Point2D *point （圆心）
2> 方法
* 属性相应的set和get方法
* 设计一个对象方法判断跟其他圆是否相交（重叠返回YES，否则返回NO）
* 设计一个类方法判断两个圆是否相交（重叠返回YES，否则返回NO）
*/
#import <Foundation/Foundation.h>
#import <math.h>
// 点
@interface Point2D : NSObject
{
double _x; // x值
double _y; // y值
}
// x值的getter和setter
- (void)setX:(double)x;
- (double)x;
// y值的getter和setter
- (void)setY:(double)y;
- (double)y;
// 同时设置x和y
- (void)setX:(double)x andY:(double)y;
// 计算跟其他点的距离
- (double)distanceWithOther:(Point2D *)other;
// 计算两个点之间的距离
+ (double)distanceBetweenPoint1:(Point2D *)p1 andPoint2:(Point2D *)p2;
@end
@implementation Point2D
// x值的getter和setter
- (void)setX:(double)x
{
_x = x;
}
- (double)x
{
return _x;
}
// y值的getter和setter
- (void)setY:(double)y
{
_y = y;
}
- (double)y
{
return _y;
}
// 同时设置x和y
- (void)setX:(double)x andY:(double)y
{
// 第1种思路
// _x = x;
// _y = y;
// 第2种思路
[self setX:x];
[self setY:y];
}
// 计算跟其他点的距离
- (double)distanceWithOther:(Point2D *)other
{
// 不要再傻乎乎算一遍了，直接调用类方法即可
return [Point2D distanceBetweenPoint1:self andPoint2:other];
}
// 计算两个点之间的距离
+ (double)distanceBetweenPoint1:(Point2D *)p1 andPoint2:(Point2D *)p2
{
// 两点距离公式：( (x1-x2)的平方 + (y1-y2)的平方 )开根
// x1-x2
double xDelta = [p1 x] - [p2 x];
// (x1-x2)的平方
double xDeltaPingFang = pow(xDelta, 2);
// y1-y2
double yDelta = [p1 y] - [p2 y];
// (y1-y2)的平方
double yDeltaPingFang = pow(yDelta, 2);
return sqrt(xDeltaPingFang + yDeltaPingFang);
}
@end
@interface Circle : Point2D
{
double _radius;
}
// radius值的setter和getter方法
- (void)setRadius:(double)radius;
- (double)radius;
- (bool)xjWithOtherCircle :(Circle *)other;
+ (bool)xjBetweenCircle1: (Circle *)c1 andCircle2:(Circle *)c2;
@end
@implementation Circle
- (void)setRadius:(double)radius
{
_radius = radius;
}
- (double)radius
{
return _radius;
}
- (bool)xjWithOtherCircle :(Circle *)other
{
return [Circle xjBetweenCircle1:self andCircle2:other];
}
+ (bool)xjBetweenCircle1: (Point2D *)c1 andCircle2:(Point2D *)c2
{
// 判断两圆是否相交：两圆心的距离和半径之和比较大小
//1、如果圆心距离大于半径之和，则不想交
//2、如果圆心半径小于或等于半径之和，则相交
double r=[c1 radius] + [c2 radius];
double dis=[Point2D diatanceBetweenPoint1:c1 andPoint2: c2];
if(r<dis)
return NO;
else
return YES;
}
@end
int main()
{
Circle *p1 = [Circle new];
[p1 setX:10 andY:10];
[p1 setRadius:3];
Circle *p2 = [Circle new];
[p2 setX:13 andY:14];
[p2 setRadius:1];
// double d1 = [p1 distanceWithOther:p2];
//
double d2 = [Point2D distanceBetweenPoint1:p1 andPoint2:p2];
NSLog(@"%d", [Circle xjBetweenCircle1:p1 andCircle2:p2]);
return 0;
}

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