C++ Fundamentals for Professionals/

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Type Traits: Categories and Transformations

Type Traits: Categories and Transformations

This lesson is an extension of the previous lesson where we'll study categories and transformations of type traits.

We'll cover the following...

Primary type categories #

C++ has 14 primary type categories. They are complete and orthogonal, meaning that each type is exactly a member of one type category. The check for the type categories is independent of the type qualifiers const or volatile.

The 14 primary type categories are as follows:

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template <class T> struct is_void;
template <class T> struct is_integral;
template <class T> struct is_floating_point;
template <class T> struct is_array;
template <class T> struct is_pointer;
template <class T> struct is_reference;
template <class T> struct is_member_object_pointer;
template <class T> struct is_member_function_pointer;
template <class T> struct is_enum;
template <class T> struct is_union;
template <class T> struct is_class;
template <class T> struct is_function;
template <class T> struct is_lvalue_reference;
template <class T> struct is_rvalue_reference;

Composite type categories #

Based on the 14 primary type categories, there are 7 composite type categories in C++.

Performance - working on the entire memory area #

This idea is quite straightforward and is used in current implementations of the STL. If the elements of a container are simple enough, the algorithm of the STL, such as std::copy, ...