TypeId not printing information as expected [duplicate]
题
Possible Duplicate:
Printing derived class name in base class
I am using GCC, and the following code output something unexpected
#include <iostream>
#include <typeinfo>
using namespace std;
class B {
public:
B ( B * ptr) { cout<< typeid(*ptr).name()<<endl;}
};
class D : public B {
public:
D() : B(this) { cout<<typeid(this).name()<<endl;}
};
int main()
{
D d;
return 0;
}
output:
1B
P1D
Can anyone please explain to me why here the base class cannot tell the type of the derived class correctly? Many thanks
解决方案
Two reasons:
- The object (
*ptr
) hasn't been fully constructed yet. - Your classes are not polymorphic (no virtual member functions), so no dynamic type information exists.
其他提示
that thing really depends on compiler. msvc provides different typeid string for that.
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