类的继承会首先寻找基类,若基类未实现,则会寻找派生类的函数 1. class继承,函数不继承 #include stdio.h class Base{public: Base(){} ~Base(){} int a; void setA() { a = 1; }}; class A:public Base{public: A(){
类的继承会首先寻找基类,若基类未实现,则会寻找派生类的函数
1. class继承,函数不继承
#include <stdio.h> class Base { public: Base(){} ~Base(){} int a; void setA() { a = 1; } }; class A:public Base { public: A(){} ~A(){} void setA() { a = 2; } }; class B:public Base { public: B(){} ~B(){} void setA() { a = 3; } }; int main() { A *ax = new A(); B *bx = new B(); Base *aClass = ax; Base *bClass = bx; aClass->setA(); bClass->setA(); printf("a value of a %d\n", aClass->a); printf("a value of b %d\n", bClass->a); return 0; }
运行结果:
2. 函数和Class都继承
#include <stdio.h> class Base { public: Base(){} ~Base(){} int a; virtual void setA() { a = 1; } }; class A:public Base { public: A(){} ~A(){} virtual void setA() { a = 2; } }; class B:public Base { public: B(){} ~B(){} virtual void setA() { a = 3; } }; int main() { A *ax = new A(); B *bx = new B(); Base *aClass = ax; Base *bClass = bx; aClass->setA(); bClass->setA(); printf("a value of a %d\n", aClass->a); printf("a value of b %d\n", bClass->a); return 0; }
运行结果:注意派生类中可以不写virtual,最好写上,以辨别是函数继承
若将2中基类的函数写为纯虚函数,运行的结果一样,但是如果基类是纯虚函数,派生类必须实现相应的函数。
class Base { public: Base(){} ~Base(){} int a; virtual void setA()=0; };
3. 类A中不有函数,则继承自基类
class A:public Base { public: A(){} ~A(){} };
结果为:
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