Apache C++ Standard Library Reference Guide

## Facets

Library: Localization

- Local Index
- Summary
- Description
- See Also
- Standards Conformance

### Local Index

No Entries

### Summary

A family of classes used to encapsulate categories of locale functionality

### Description

The Standard C++ Localization library includes a locale interface that contains a collection of diverse facets. Each facet has localization facilities for some specific area, such as character classification or numeric formatting. Each facet also falls into one or more broad categories. These categories are defined in the locale class, and the standard facets fit into these categories as follows.

#### Table 18: Categories and facets of the locale class

Category | Facets
`collate` | `collate, collate_byname`
`ctype` | `ctype, codecvt, ctype_byname, codecvt_byname`
`monetary` | `moneypunct, moneypunct_byname, money_put, money_get`
`numeric` | `numpunct, numpunct_byname, num_put, num_get`
`time` | `time_put, time_put_byname, time_get, time_get_byname`
`messages` | `messages, messages_byname`

A facet must satisfy two properties. First, it must be derived from the base class `locale::facet`, either directly or indirectly (for example, `facet -> ctype<char> -> my_ctype`). Second, it must contain a member of type `locale::id`. This ensures that the locale class can manage its collection of facets properly.

### See Also

locale, collate, collate_byname, ctype, codecvt, ctype_byname, codecvt_byname, moneypunct, moneypunct_byname, money_put, money_get, numpunct, numpunct_byname, num_put, num_get, time_put, time_put_byname, time_get, time_get_byname, messages, messages_byname

### Standards Conformance

ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 22.2.8