C++类继承 继承后函数的值实现详解
时间：2020-11-15 13:21:14 | 栏目：C代码 | 点击：次
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：
