21 Metaprogramming library [meta]

21.3 Metaprogramming and type traits [type.traits]

The templates specified in Table 57 add or remove cv-qualifications ([basic.type.qualifier]).

Table 57 — Const-volatile modifications [tab:meta.trans.cv]

ð Template	Comments
ð template struct remove_const;	The member typedef type denotes the type formed by removing any top-level const-qualifier from T. [Example 1: remove_const_t evaluates to volatile int, whereas remove_const_t<const int> evaluates to const int. â end example]
ð template struct remove_volatile;	The member typedef type denotes the type formed by removing any top-level volatile-qualifier from T. [Example 2: remove_volatile_t evaluates to const int, whereas remove_volatile_t<volatile int> evaluates to volatile int. â end example]
ð template struct remove_cv;	The member typedef type denotes the type formed by removing any top-level cv-qualifiers from T. [Example 3: remove_cv_t evaluates to int, whereas remove_cv_t<const volatile int> evaluates to const volatile int. â end example]
ð template struct add_const;	The member typedef type denotes const T. [Note 1: const has no effect when T is a reference, function, or top-level const-qualified type. â end note]
ð template struct add_volatile;	The member typedef type denotes volatile T. [Note 2: volatile has no effect when T is a reference, function, or top-level volatile-qualified type. â end note]
ð template struct add_cv;	The member typedef type denotes add_const_t<add_volatile_t>.