[locale.category]

# 28 Text processing library [[text]](./#text)

## 28.3 Localization library [[localization]](localization#locale.category)

### 28.3.3 Locales [[locales]](locales#locale.category)

#### 28.3.3.1 Class locale [[locale]](locale#category)

#### 28.3.3.1.2 Types [[locale.types]](locale.types#locale.category)

#### 28.3.3.1.2.1 Type locale​::​category [locale.category]

[🔗](#lib:locale,category)

`using category = int;
`

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/text.tex#L633)

*Valid* category values
include the locale member bitmask elementscollate,ctype,monetary,numeric,time,
andmessages,
each of which represents a single locale category[.](#1.sentence-1)

In addition, locale member bitmask constant none is defined as zero and represents no category[.](#1.sentence-2)

And locale member bitmask constant all is defined such that the expression(collate | ctype | monetary | numeric | time | messages | all) == all is true,
and represents the union of all categories[.](#1.sentence-3)

Further, the expression (X | Y),
where X and Y each represent a single category,
represents the union of the two categories[.](#1.sentence-4)

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/text.tex#L657)

locale member functions
expecting a category argument
require one of the category values defined above, or
the union of two or more such values[.](#2.sentence-1)

Such a category value identifies a set of locale categories[.](#2.sentence-2)

Each locale category, in turn, identifies a set of locale facets,
including at least those shown in Table [91](#tab:locale.category.facets "Table 91: Locale category facets")[.](#2.sentence-3)

Table [91](#tab:locale.category.facets) — Locale category facets [[tab:locale.category.facets]](./tab:locale.category.facets)  

| [🔗](#tab:locale.category.facets-row-1)<br>**Category** | **Includes facets** |
| --- | --- |
| [🔗](#tab:locale.category.facets-row-2)<br>collate | collate<char>, collate<wchar_t> |
| [🔗](#tab:locale.category.facets-row-3)<br>ctype | ctype<char>, ctype<wchar_t> |
| [🔗](#tab:locale.category.facets-row-4) | codecvt<char, char, mbstate_t> |
| [🔗](#tab:locale.category.facets-row-5) | codecvt<wchar_t, char, mbstate_t> |
| [🔗](#tab:locale.category.facets-row-6)<br>monetary | moneypunct<char>, moneypunct<wchar_t> |
| [🔗](#tab:locale.category.facets-row-7) | moneypunct<char, true>, moneypunct<wchar_t, true> |
| [🔗](#tab:locale.category.facets-row-8) | money_get<char>, money_get<wchar_t> |
| [🔗](#tab:locale.category.facets-row-9) | money_put<char>, money_put<wchar_t> |
| [🔗](#tab:locale.category.facets-row-10)<br>numeric | numpunct<char>, numpunct<wchar_t> |
| [🔗](#tab:locale.category.facets-row-11) | num_get<char>, num_get<wchar_t> |
| [🔗](#tab:locale.category.facets-row-12) | num_put<char>, num_put<wchar_t> |
| [🔗](#tab:locale.category.facets-row-13)<br>time | time_get<char>, time_get<wchar_t> |
| [🔗](#tab:locale.category.facets-row-14) | time_put<char>, time_put<wchar_t> |
| [🔗](#tab:locale.category.facets-row-15)<br>messages | messages<char>, messages<wchar_t> |

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/text.tex#L686)

For any locale loc either constructed, or returned by locale​::​classic(),
and any facet Facet shown in Table [91](#tab:locale.category.facets "Table 91: Locale category facets"),has_facet<Facet>(loc) is true[.](#3.sentence-1)

Each locale member function
which takes a locale​::​category argument
operates on the corresponding set of facets[.](#3.sentence-2)

[4](#4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/text.tex#L695)

An implementation is required to provide those specializations
for facet templates identified as members of a category, and
for those shown in Table [92](#tab:locale.spec "Table 92: Required specializations")[.](#4.sentence-1)

Table [92](#tab:locale.spec) — Required specializations [[tab:locale.spec]](./tab:locale.spec)  

| [🔗](#tab:locale.spec-row-1)<br>**Category** | **Includes facets** |
| --- | --- |
| [🔗](#tab:locale.spec-row-2)<br>collate | collate_byname<char>, collate_byname<wchar_t> |
| [🔗](#tab:locale.spec-row-3)<br>ctype | ctype_byname<char>, ctype_byname<wchar_t> |
| [🔗](#tab:locale.spec-row-4) | codecvt_byname<char, char, mbstate_t> |
| [🔗](#tab:locale.spec-row-5) | codecvt_byname<wchar_t, char, mbstate_t> |
| [🔗](#tab:locale.spec-row-6)<br>monetary | moneypunct_byname<char, International> |
| [🔗](#tab:locale.spec-row-7) | moneypunct_byname<wchar_t, International> |
| [🔗](#tab:locale.spec-row-8) | money_get<C, InputIterator> |
| [🔗](#tab:locale.spec-row-9) | money_put<C, OutputIterator> |
| [🔗](#tab:locale.spec-row-10)<br>numeric | numpunct_byname<char>, numpunct_byname<wchar_t> |
| [🔗](#tab:locale.spec-row-11) | num_get<C, InputIterator>, num_put<C, OutputIterator> |
| [🔗](#tab:locale.spec-row-12)<br>time | time_get<char, InputIterator> |
| [🔗](#tab:locale.spec-row-13) | time_get_byname<char, InputIterator> |
| [🔗](#tab:locale.spec-row-14) | time_get<wchar_t, InputIterator> |
| [🔗](#tab:locale.spec-row-15) | time_get_byname<wchar_t, InputIterator> |
| [🔗](#tab:locale.spec-row-16) | time_put<char, OutputIterator> |
| [🔗](#tab:locale.spec-row-17) | time_put_byname<char, OutputIterator> |
| [🔗](#tab:locale.spec-row-18) | time_put<wchar_t, OutputIterator> |
| [🔗](#tab:locale.spec-row-19) | time_put_byname<wchar_t, OutputIterator> |
| [🔗](#tab:locale.spec-row-20)<br>messages | messages_byname<char>, messages_byname<wchar_t> |

[5](#5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/text.tex#L726)

The provided implementation of members of
facets num_get<charT> and num_put<charT> calls use_facet<F>(l) only for facet F of
types numpunct<charT> and ctype<charT>,
and for locale l the value obtained by calling member getloc() on the ios_base& argument to these functions[.](#5.sentence-1)

[6](#6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/text.tex#L734)

In declarations of facets,
a template parameter with name InputIterator or OutputIterator indicates the set of all possible specializations on parameters that meet the*Cpp17InputIterator* requirements or*Cpp17OutputIterator* requirements,
respectively ([[iterator.requirements]](iterator.requirements "24.3 Iterator requirements"))[.](#6.sentence-1)

A template parameter with name C represents
the set of types containing char, wchar_t, and any otherimplementation-defined
character container types ([[defns.character.container]](defns.character.container "3.10 character container type"))
that meet the requirements for a character
on which any of the iostream components can be instantiated[.](#6.sentence-2)

A template parameter with name International represents the set of all possible specializations on a bool parameter[.](#6.sentence-3)