Using type traits to query properties of types

Template metaprogramming is a powerful feature of the language that enables us to write and reuse generic code that works with all types. In practice, however, it is often necessary that generic code should work differently, or not at all, with different types, either through intent or for semantic correctness, performance, or other reasons. For example, you may want a generic algorithm to be implemented differently for POD and non-POD types or a function template to be instantiated only with integral types. C++11 provides a set of type traits to help with this.

Type traits are basically meta-types that provide information about other types. The type traits library contains a long list of traits for querying type properties (such as checking whether a type is an integral type or whether two types are the same), but also for performing type transformation (such as removing the const and volatile qualifiers or adding a pointer to a...