---
description: "Learn more about: bad_typeid exception"
title: "bad_typeid exception"
ms.date: "10/04/2019"
f1_keywords: ["bad_typeid", "bad_typeid_cpp"]
helpviewer_keywords: ["bad_typeid exception", "exceptions [C++], bad_typeid"]
ms.assetid: 5963ed58-4ede-4597-957d-f7bbd06299c2
---
# bad_typeid exception

The **bad_typeid** exception is thrown by the [typeid operator](../cpp/typeid-operator.md) when the operand for **`typeid`** is a NULL pointer.

## Syntax

```
catch (bad_typeid)
   statement
```

## Remarks

The interface for **bad_typeid** is:

```cpp
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.

```cpp
// 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

```Output
Object is NULL
```

## See also

[Run-Time Type Information](../cpp/run-time-type-information.md)\
[Keywords](../cpp/keywords-cpp.md)