The above answers are correct. I would like to add some 
details to those.

1. const_cast:- is used to cast away the constness of a 
variable.

2. static_cast:- is used to cast between two types with the 
available static information about the variable. It doesn't 
know anything about the run time information. Additionally, 
it knows the type and access previledges of the 
variables/objects involved in the casting. For example, we 
cannot cast a private base.

3. reinterpret_cast:- is used to cast between any pointer 
types and the types need not be related. The developer 
needs to take care of the correct types to be casted.

4. dynamic_cast:- is used to cast between polymorphic types 
only. It allows downcasting and casting between siblings as 
well. If the cast fails, it returns a 0/NULL instead of the 
pointer to the resultant object incase of success.