Type-Casting.

[zb0S216C]

I have read about type-casting with these operators:

reinterpret_cast< TYPE-ID >( EXPRESSION );
dynamic_cast< TYPE-ID >( EXPRESSION );
static_cast< TYPE-ID >( EXPRESSION );
const_cast< TYPE-ID >( EXPRESSION );
( TYPE-ID )EXPRESSION;

I have read about theses on multiple sites( including this one ) and I still don't know when to use them or how to implement them. Any suggestions on how I should use these?

[Bazzy]

You should avoid const_cast and reinterpret_cast
dynamic_cast is useful when you have polymorphic classes and you want to access a feature present only on a derived class
static_cast or C-style cast to convert between basic types

[hanst99]

static_cast is the c++ equivalent to the C-style cast:
(Type-Id) variable

dynamic_cast casts a variable of a supertype into a variable of a subtype. Can only be used with pointers and references, I guess the reason is obvious.

const_cast casts a type into a const type and vice versa.

reinterpret_cast basically changes the type of the variable without changing the bit sequence. Very unsafe, you'd better have a good reason when using that one.

In general you should avoid casts. If you use only your own code you should rarely ever come into a situation where casts are necessary, and if they look necessary you should check your design for faults first. There are situations in which they are useful though.

[zb0S216C]

Thanks Bazzy and hanst99! I now understand what each type-casting operator does and how it's used.

[Kanj]

I understand that reinterpret_cast changes the type of the variable without changing the bit sequence.
But can anyone explain how C-style cast works or how it's different?
I'm reading a book which uses reinterpret_cast in example programs but switches to C-style casting in similar situations in later examples without any explanation.
Both are used to read/write a class object to files and both are working well for me.

[Kyon]

The difference is that static_cast does not check whether the output is valid and reinterpret_cast can only be used for pointers and references. If a class cannot be converted to a related class, reinterpret_cast returns a NULL pointer, whereas static_cast would produce an invalid output.