下面的内容要说明两个问题：1. 基类的析构函数为什么要加上Virtual--防止内存泄露
1. 基类虚构函数无virtual，派生类无法析构，会导致内存泄露
#include <stdio.h> class Base
{
public:
int a;
Base(){
a=0;
}
~Base(){
printf("base delete");
}
virtual void setA()=0;
}; class A:public Base
{
public:
A(){
a = 10;
}
~A(){
printf("A class delete\n");
}
virtual void setA()
{
a = 2;
}
}; class B:public Base
{
public:
B(){
a=20;
}
~B(){
a=-20;
} virtual void setA()
{
a = 3;
}
}; int main()
{ Base *ax = new A();
Base *bx = new B();
Base *aClass = ax;
Base *bClass = bx;
printf("a value of a construct %d\n", aClass->a);
printf("a value of b construct %d\n", bClass->a); aClass->setA();
bClass->setA();
printf("a value of a %d\n", aClass->a);
printf("a value of b %d\n", bClass->a); delete aClass; return 0;
}
运行结果为：
2. 若在基类析构函数前加上Virtual
class Base
{
public:
int a;
Base(){
a=0;
}
virtual ~Base(){
printf("base delete");
}
virtual void setA()=0; };
运行结果为：