Last modified on 1 January 2013, at 15:28

C++ Programming

The const_cast keyword can be used to remove the const or volatile property from an object. The target data type must be the same as the source type, except (of course) that the target type doesn't have to have the same const qualifier. The type TYPE must be a pointer or reference type.

Syntax
    TYPE* const_cast<TYPE*> (object);
    TYPE& const_cast<TYPE&> (object);

For example, the following code uses const_cast to remove the const qualifier from a object:

class Foo {
public:
  void func() {} // a non-const member function
};
 
void someFunction( const Foo& f )  {
  f.func();      // compile error: cannot call a non-const 
                 // function on a const reference 
  Foo &fRef = const_cast<Foo&>(f);
  fRef.func();   // okay
}