Category 

Operators, C++-Specific Keywords 

Syntax  

typeid( expression )
typeid( type-name )

Description 

You can use typeid to get runtime identification of types and expressions. A call to typeid returns a reference to an object of type const type_info. The returned object represents the type of the typeid operand. 

If the typeid operand is a dereferenced pointer or a reference to a polymorphic type, typeid returns the dynamic type of the actual object pointed or referred to. If the operand is non-polymorphic, typeid returns an object that represents the static type. 

You can use the typeid operator with fundamental data types as well as user-defined types. 

When the typeid operand is a Delphi class object/reference, typeid returns the static rather than runtime type.  

If the typeid operand is a dereferenced NULL pointer, the Bad_typeid exception is thrown.