typeid 的用法

Base *bp;

Derived *dp;

// compare type at run time of two objects

if (typeid(*bp) == typeid(*dp)) {

// bp and dp point to objects of the same type

}

// test whether run time type is a specific type

if (typeid(*bp) == typeid(Derived)) {

// bp actually points to a Derived

}

注意，typeid 的操作数是表示对象的表达式——测试 *bp，而不是 bp：

Base *bp = new Derived ;

cout<<typeid(bp)<<endl;   //输出 Class Base *

cout<<typeid(*bp)<<endl;  //输出 Class Derived