When should static_cast, dynamic_cast, const_cast and reinterpret_cast be used?

const_cast

can be used to remove or add const to a variable. This can be useful if it is necessary to add/remove constness from a variable.

static_cast

This is used for the normal/ordinary type conversion. This is also the cast responsible for implicit type coercion and can also be called explicitly. You should use it in cases like converting float to int, char to int, etc.

dynamic_cast

This cast is used for handling polymorphism. You only need to use it when you're casting to a derived class. This is exclusively to be used in inheritance when you cast from base class to derived class.

reinterpret_cast

This is the trickiest to use. It is used for reinterpreting bit patterns and is extremely low level. It's used primarily for things like turning a raw data bit stream into actual data, or storing data in the low bits of an aligned pointer.