bad-typeid-exception.md

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Learn more about: bad_typeid exception	bad_typeid exception	10/04/2019	bad_typeid bad_typeid_cpp	bad_typeid exception exceptions [C++], bad_typeid	5963ed58-4ede-4597-957d-f7bbd06299c2

bad_typeid exception

The bad_typeid exception is thrown by the typeid operator when the operand for typeid is a NULL pointer.

Syntax

catch (bad_typeid)
   statement

Remarks

The interface for bad_typeid is:

class bad_typeid : public exception
{
public:
   bad_typeid();
   bad_typeid(const char * _Message = "bad typeid");
   bad_typeid(const bad_typeid &);
   virtual ~bad_typeid();

   bad_typeid& operator=(const bad_typeid&);
   const char* what() const;
};

The following example shows the typeid operator throwing a bad_typeid exception.

// expre_bad_typeid.cpp
// compile with: /EHsc /GR
#include <typeinfo>
#include <iostream>

class A{
public:
   // object for class needs vtable
   // for RTTI
   virtual ~A();
};

using namespace std;
int main() {
A* a = NULL;

try {
   cout << typeid(*a).name() << endl;  // Error condition
   }
catch (bad_typeid){
   cout << "Object is NULL" << endl;
   }
}

Output

Object is NULL

See also

Run-Time Type Information
Keywords