1、继承
动物有 吃 睡 呼吸的方法 当然 鱼也有 不用重复再定义
1）public 那里都可以访问
1 #include <iostream.h>
2 class Animal //类 基类
3 {
4 public:
5 void eat()//吃方法
6 {
7 cout<<"animal eat "<<endl;
8
9 }
10 void sleep()//睡觉方法
11 {
12 cout<<"animal sleep"<<endl;
13 }
14 void breathe()//呼吸方法
15 {
16 cout<<"animal breathe"<<endl;
17 }
18 };
19 class Fish: public Animal// //子类
20 {
21
22
23 };
24
25 void main()
26
27 {
28 Animal an;
29 an.eat();
30 Fish fh;
31 fh.sleep();
32 }
View Code
2）protected 只有子类能访问 外部其他的都不能被访问
1 #include <iostream.h>
2 class Animal //类 基类
3 {
4 public:
5 void eat()//吃方法
6 {
7 cout<<"animal eat "<<endl;
8
9 }
10 protected:
11 void sleep()//睡觉方法
12 {
13 cout<<"animal sleep"<<endl;
14 }
15 void breathe()//呼吸方法
16 {
17 cout<<"animal breathe"<<endl;
18 }
19 };
20 class Fish: public Animal// //子类
21 {
22 void test()
23 {
24 sleep();
25 breathe();
26 }
27
28 };
29
30 void main()
31
32 {
33 Animal an;
34 an.eat();
35 Fish fh;
36 fh.sleep();
37 }
View Code
3）private 只有自己能访问 ，子类 外部都不能访问
1 #include <iostream.h>
2 class Animal //类 基类
3 {
4 public:
5 void eat()//吃方法
6 {
7 cout<<"animal eat "<<endl;
8
9 }
10 protected:
11 void sleep()//睡觉方法
12 {
13 cout<<"animal sleep"<<endl;
14 }
15 private:
16 void breathe()//呼吸方法
17 {
18 cout<<"animal breathe"<<endl;
19 }
20 };
21 class Fish: public Animal// //子类
22 {
23 void test()
24 {
25 sleep();
26 breathe();
27 }
28
29 };
30
31 void main()
32
33 {
34 Animal an;
35 an.eat();
36 Fish fh;
37 // fh.sleep();
38 }
View Code
4）访问特性
最多为public继承
2、继承的先后性
没有父亲 就没有孩子
1）基类 子类 构造函数的调用顺序
动物先
1 #include <iostream.h>
2 class Animal //类 基类
3 {
4 public:
5
6 Animal()
7 {
8 cout<<"Animal construct "<<endl;
9 }
10 void eat()//吃方法
11 {
12 cout<<"animal eat "<<endl;
13
14 }
15 //protected:
16 void sleep()//睡觉方法
17 {
18 cout<<"animal sleep"<<endl;
19 }
20 //private:
21 void breathe()//呼吸方法
22 {
23 cout<<"animal breathe"<<endl;
24 }
25 };
26 class Fish: public Animal// 继承特性 //子类
27 {
28 public:
29 Fish()
30 {
31 cout<<"Fish construct "<<endl;
32 }
33
34 };
35
36 void main()
37
38 {
39 // Animal an;
40 // an.eat();
41 Fish fh;
42 // fh.sleep();
43 }
View Code
2）基类 子类 析构函数的调用顺序
鱼先
1 #include <iostream.h>
2 class Animal //类 基类
3 {
4 public:
5
6 Animal()
7 {
8 cout<<"Animal construct "<<endl;
9 }
10 ~Animal()
11 {
12 cout<<"Animal deconstruct "<<endl;
13 }
14 void eat()//吃方法
15 {
16 cout<<"animal eat "<<endl;
17
18 }
19 //protected:
20 void sleep()//睡觉方法
21 {
22 cout<<"animal sleep"<<endl;
23 }
24 //private:
25 void breathe()//呼吸方法
26 {
27 cout<<"animal breathe"<<endl;
28 }
29 };
30 class Fish: public Animal// 继承特性 //子类
31 {
32 public:
33 Fish()
34 {
35 cout<<"Fish construct "<<endl;
36 }
37 ~Fish()
38 {
39 cout<<"Fish deconstruct "<<endl;
40 }
41 };
42
43 void main()
44
45 {
46 // Animal an;
47 // an.eat();
48 Fish fh;
49 // fh.sleep();
50 }
View Code
3、继承出错：没有对象的基类 子类初始化 基类没有初始化 且基类有参数
子类只能初始化无 参数的 基类
错误：无 缺省的 基类可条用
1 #include <iostream.h>
2 class Animal //类 基类
3 {
4 public:
5
6 Animal(int height , int weight)
7 {
8 cout<<"Animal construct "<<endl;
9 }
10 ~Animal()
11 {
12 cout<<"Animal deconstruct "<<endl;
13 }
14 void eat()//吃方法
15 {
16 cout<<"animal eat "<<endl;
17
18 }
19 //protected:
20 void sleep()//睡觉方法
21 {
22 cout<<"animal sleep"<<endl;
23 }
24 //private:
25 void breathe()//呼吸方法
26 {
27 cout<<"animal breathe"<<endl;
28 }
29 };
30 class Fish: public Animal// 继承特性 //子类
31 {
32 public:
33 Fish()
34 {
35 cout<<"Fish construct "<<endl;
36 }
37 ~Fish()
38 {
39 cout<<"Fish deconstruct "<<endl;
40 }
41 };
42
43 void main()
44
45 {
46 // Animal an;
47 // an.eat();
48 Fish fh;
49 // fh.sleep();
50 }
View Code
解决：象基类中传递参数 Fish():Animal(400,300)
1 #include <iostream.h>
2 class Animal //类 基类
3 {
4 public:
5
6 Animal(int height , int weight)
7 {
8 cout<<"Animal construct "<<endl;
9 }
10 ~Animal()
11 {
12 cout<<"Animal deconstruct "<<endl;
13 }
14 void eat()//吃方法
15 {
16 cout<<"animal eat "<<endl;
17
18 }
19 //protected:
20 void sleep()//睡觉方法
21 {
22 cout<<"animal sleep"<<endl;
23 }
24 //private:
25 void breathe()//呼吸方法
26 {
27 cout<<"animal breathe"<<endl;
28 }
29 };
30 class Fish: public Animal// 继承特性 //子类
31 {
32 public:
33 Fish():Animal(400,300)
34 {
35 cout<<"Fish construct "<<endl;
36 }
37 ~Fish()
38 {
39 cout<<"Fish deconstruct "<<endl;
40 }
41 };
42
43 void main()
44
45 {
46 // Animal an;
47 // an.eat();
48 Fish fh;
49 // fh.sleep();
50 }
View Code
4）常量初始化
1 class Fish: public Animal// 继承特性 //子类
2 {
3 public:
4 Fish():Animal(400,300),a(1)
5 {
6 // cout<<"Fish construct "<<endl;
7 }
8 ~Fish()
9 {
10 // cout<<"Fish deconstruct "<<endl;
11 }
12 private :
13 const int a;
14 };
View Code
4、函数的覆盖
1）不要基类的
父亲结婚：花轿
儿子击婚：轿车
1 #include <iostream.h>
2 class Animal //类 基类
3 {
4 public:
5
6 Animal(int height , int weight)
7 {
8 // cout<<"Animal construct "<<endl;
9 }
10 ~Animal()
11 {
12 // cout<<"Animal deconstruct "<<endl;
13 }
14 void eat()//吃方法
15 {
16 cout<<"animal eat "<<endl;
17
18 }
19 //protected:
20 void sleep()//睡觉方法
21 {
22 cout<<"animal sleep"<<endl;
23 }
24 //private:
25 void breathe()//呼吸方法
26 {
27 cout<<"animal breathe"<<endl;
28 }
29 };
30 class Fish: public Animal// 继承特性 //子类
31 {
32 public:
33 Fish():Animal(400,300),a(1)
34 {
35 // cout<<"Fish construct "<<endl;
36 }
37 ~Fish()
38 {
39 // cout<<"Fish deconstruct "<<endl;
40 }
41 void sleep()
42 {
43 cout<<"jjjjjjjjjj"<<endl;
44 }
45 private :
46 const int a;
47 };
48
49 void main()
50
51 {
52 // Animal an;
53 // an.eat();
54 Fish fh;
55 fh.sleep();
56 }
View Code
1）两个都要
父亲结婚：花轿
儿子击婚：轿车 花轿
1 #include <iostream.h>
2 class Animal //类 基类
3 {
4 public:
5
6 Animal(int height , int weight)
7 {
8 // cout<<"Animal construct "<<endl;
9 }
10 ~Animal()
11 {
12 // cout<<"Animal deconstruct "<<endl;
13 }
14 void eat()//吃方法
15 {
16 cout<<"animal eat "<<endl;
17
18 }
19 //protected:
20 void sleep()//睡觉方法
21 {
22 cout<<"animal sleep"<<endl;
23 }
24 //private:
25 void breathe()//呼吸方法
26 {
27
28 cout<<"animal breathe"<<endl;
29 }
30 };
31 class Fish: public Animal// 继承特性 //子类
32 {
33 public:
34 Fish():Animal(400,300),a(1)
35 {
36 // cout<<"Fish construct "<<endl;
37 }
38 ~Fish()
39 {
40 // cout<<"Fish deconstruct "<<endl;
41 }
42 void sleep()
43 {
44 Animal::sleep();
45 cout<<"jjjjjjjjjj"<<endl;
46 }
47 private :
48 const int a;
49 };
50
51 void main()
52
53 {
54 // Animal an;
55 // an.eat();
56 Fish fh;
57 fh.sleep();
58 }
View Code
5、对象转换
类型转换
int--char 丢失精度 截掉了三个字节
char--int ok 允许
对象转换：
内存模型相同才能转换
输出的是 动物的 而不是 鱼的
1 #include <iostream.h>
2 class Animal //类 基类
3 {
4 public:
5
6 Animal(int height , int weight)
7 {
8 // cout<<"Animal construct "<<endl;
9 }
10 ~Animal()
11 {
12 // cout<<"Animal deconstruct "<<endl;
13 }
14 void eat()//吃方法
15 {
16 cout<<"animal eat "<<endl;
17
18 }
19 //protected:
20 void sleep()//睡觉方法
21 {
22 cout<<"animal sleep"<<endl;
23 }
24 //private:
25 void breathe()//呼吸方法
26 {
27
28 cout<<"animal breathe"<<endl;
29 }
30 };
31 class Fish: public Animal// 继承特性 //子类
32 {
33 public:
34 Fish():Animal(400,300),a(1)
35 {
36 // cout<<"Fish construct "<<endl;
37 }
38 ~Fish()
39 {
40 // cout<<"Fish deconstruct "<<endl;
41 }
42 void sleep()
43 {
44 Animal::sleep();//作用域标示符
45 cout<<"jjjjjjjjjj"<<endl;
46 }
47 private :
48 const int a;
49 };
50 void fn(Animal *pAn)
51 {
52 pAn->sleep();
53 }
54 void main()
55
56 {
57 // Animal an;
58 // an.eat();
59 Fish fh;
60 Animal *pAn;
61 pAn=&fh;
62 fn(pAn);
63 // fh.sleep();
64 }
View Code
原文链接: https://www.cnblogs.com/TFH-FPGA/p/3192398.html
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