std::basic_regex

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Text processing library

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Regular expressions library(C++11)

Formatting library(C++20)

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Byte strings

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to_chars (C++17)
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chars_format (C++17)

Text encoding identifications

text_encoding

(C++26)

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Regular expressions library

Classes
basic_regex (C++11)
sub_match (C++11)
match_results (C++11)
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regex_match (C++11)
regex_search (C++11)
regex_replace (C++11)
Iterators
regex_iterator (C++11)
regex_token_iterator (C++11)
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regex_error (C++11)
Traits
regex_traits (C++11)
Constants
syntax_option_type (C++11)
match_flag_type (C++11)
error_type (C++11)
Regex Grammar
Modified ECMAScript-262 (C++11)

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std::basic_regex

Member Functions
basic_regex::basic_regex
basic_regex::~basic_regex
basic_regex::operator=
basic_regex::assign
Observers
basic_regex::mark_count
basic_regex::flags
Locale
basic_regex::getloc
basic_regex::imbue
Modifiers
basic_regex::swap
Constants
Non-member Functions
swap(std::basic_regex)
Deduction guides(C++17)

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Defined in header`<regex>`
template< class CharT, class Traits=std::regex_traits<CharT> >class basic_regex;		(since C++11)

The class templatebasic_regex provides a general framework for holding regular expressions.

Several typedefs for common character types are provided:

Defined in header`<regex>`
Type	Definition
`std::regex`	std::basic_regex<char>
`std::wregex`	std::basic_regex<wchar_t>

[edit]Member types

Member type	Definition
`value_type`	`CharT`
`traits_type`	`Traits`
`string_type`	`Traits::string_type`
`locale_type`	`Traits::locale_type`
`flag_type`	std::regex_constants::syntax_option_type

[edit]Member functions

(constructor)	constructs the regex object (public member function)[edit]
(destructor)	destructs the regex object (public member function)[edit]
operator=	assigns the contents (public member function)[edit]
assign	assigns the contents (public member function)[edit]
Observers
mark_count	returns the number of marked sub-expressions within the regular expression (public member function)[edit]
flags	returns the syntax flags (public member function)[edit]
Locale
getloc	get locale information (public member function)[edit]
imbue	set locale information (public member function)[edit]
Modifiers
swap	swaps the contents (public member function)[edit]
Constants

Grammar option	Effect(s)
`ECMAScript`	Use theModified ECMAScript regular expression grammar.
`basic`	Use the basic POSIX regular expression grammar (grammar documentation).
`extended`	Use the extended POSIX regular expression grammar (grammar documentation).
`awk`	Use the regular expression grammar used by theawk utility in POSIX (grammar documentation).
`grep`	Use the regular expression grammar used by thegrep utility in POSIX. This is effectively the same as the`basic` option with the addition of newline'\n' as an alternation separator.
`egrep`	Use the regular expression grammar used by thegrep utility, with the-E option, in POSIX. This is effectively the same as the`extended` option with the addition of newline'\n' as an alternation separator in addition to'\|'.
Grammar variation	Effect(s)
`icase`	Character matching should be performed without regard to case.
`nosubs`	When performing matches, all marked sub-expressions`(expr)` are treated as non-marking sub-expressions`(?:expr)`. No matches are stored in the suppliedstd::regex_match structure andmark_count() is zero.
`optimize`	Instructs the regular expression engine to make matching faster, with the potential cost of making construction slower. For example, this might mean converting a non-deterministic FSA to a deterministic FSA.
`collate`	Character ranges of the form"[a-b]" will be locale sensitive.
`multiline`(C++17)	Specifies that`^` shall match the beginning of a line and`$` shall match the end of a line, if the ECMAScript engine is selected.

At most one grammar option can be chosen out ofECMAScript,basic,extended,awk,grep,egrep. If no grammar is chosen,ECMAScript is assumed to be selected. The other options serve as variations, such thatstd::regex("meow", std::regex::icase) is equivalent tostd::regex("meow", std::regex::ECMAScript|std::regex::icase).