`<regex>`

Article
02/25/2022

Defines a class template to parse Regular Expressions (C++), and several class templates and functions to search text for matches to a regular expression object.

Syntax

#include <regex>

Remarks

To create a regular expression object, use the class template basic_regex Class or one of its specializations, regex and wregex, together with the syntax flags of type regex_constants::syntax_option_type.

To search text for matches to a regular expression object, use the template functions regex_match and regex_search, together with the match flags of type regex_constants::match_flag_type. These functions return results by using the class template match_results Class and its specializations, cmatch, wcmatch, smatch, and wsmatch, together with the class template sub_match Class and its specializations, csub_match, wcsub_match, ssub_match, and wssub_match.

To replace text that matches a regular expression object, use the template function regex_replace, together with the match flags of type regex_constants::match_flag_type.

To iterate through multiple matches of a regular expression object, use the class templates regex_iterator Class and regex_token_iterator Class or one of their specializations, cregex_iterator, sregex_iterator, wcregex_iterator, wsregex_iterator, cregex_token_iterator, sregex_token_iterator, wcregex_token_iterator, or wsregex_token_iterator, together with the match flags of type regex_constants::match_flag_type.

To modify the details of the grammar of regular expressions, write a class that implements the regular expression traits.

Classes

Class	Description
`basic_regex`	Wraps a regular expression.
`match_results`	Holds a sequence of submatches.
`regex_constants`	Holds assorted constants.
`regex_error`	Reports a bad regular expression.
`regex_iterator`	Iterates through match results.
`regex_traits`	Describes characteristics of elements for matching.
`regex_traits<char>`	Describes characteristics of `char` for matching.
`regex_traits<wchar_t>`	Describes characteristics of `wchar_t` for matching.
`regex_token_iterator`	Iterates through submatches.
`sub_match`	Describes a submatch.

Type Definitions

Name	Description
`cmatch`	Type definition for `char` `match_results`.
`cregex_iterator`	Type definition for `char` `regex_iterator`.
`cregex_token_iterator`	Type definition for `char` `regex_token_iterator`.
`csub_match`	Type definition for `char` `sub_match`.
`regex`	Type definition for `char` `basic_regex`.
`smatch`	Type definition for `string` `match_results`.
`sregex_iterator`	Type definition for `string` `regex_iterator`.
`sregex_token_iterator`	Type definition for `string` `regex_token_iterator`.
`ssub_match`	Type definition for `string` `sub_match`.
`wcmatch`	Type definition for `wchar_t` `match_results`.
`wcregex_iterator`	Type definition for `wchar_t` `regex_iterator`.
`wcregex_token_iterator`	Type definition for `wchar_t` `regex_token_iterator`.
`wcsub_match`	Type definition for `wchar_t` `sub_match`.
`wregex`	Type definition for `wchar_t` `basic_regex`.
`wsmatch`	Type definition for `wstring` `match_results`.
`wsregex_iterator`	Type definition for `wstring` `regex_iterator`.
`wsregex_token_iterator`	Type definition for `wstring` `regex_token_iterator`.
`wssub_match`	Type definition for `wstring` `sub_match`.

Functions

Function	Description
`regex_match`	Exactly matches a regular expression.
`regex_replace`	Replaces matched regular expressions.
`regex_search`	Searches for a regular expression match.
`swap`	Swaps `basic_regex` or `match_results` objects.

Operators

Operator	Description
`operator==`	Comparison of various objects, equal.
`operator!=`	Comparison of various objects, not equal.
`operator<`	Comparison of various objects, less than.
`operator\<=`	Comparison of various objects, less than or equal.
`operator>`	Comparison of various objects, greater than.
`operator>=`	Comparison of various objects, greater than or equal.
`operator<<`	Inserts a `sub_match` in a stream.

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