std::sub_match

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Execution support library (C++26)

Technical specifications

Symbols index

External libraries

 

Regular expressions library

Classes

basic_regex (C++11)

sub_match (C++11)

match_results (C++11)

Algorithms

regex_match (C++11)

regex_search (C++11)

regex_replace (C++11)

Iterators

regex_iterator (C++11)

regex_token_iterator (C++11)

Exceptions

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)

 

std::sub_match

Member functions

sub_match::sub_match

sub_match::length

sub_match::strsub_match::operator string_type

sub_match::compare

Non-member functions

operator==operator!=operator<<operator<=operator>operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)

operator<<

 

Defined in header <regex>
template<     class BidirIt > class sub_match;		(since C++11)

The class template sub_match is used by the regular expression engine to denote sequences of characters matched by marked sub-expressions. A match is a [begin, end) pair within the target range matched by the regular expression, but with additional observer functions to enhance code clarity.

Only the default constructor is publicly accessible. Instances of sub_match are normally constructed and populated as a part of a std::match_results container during the processing of one of the regex algorithms.

The member functions return defined default values unless the matched member is true.

sub_match inherits from std::pair<BidirIt, BidirIt>, although it cannot be treated as a std::pair object because member functions such as swap and assignment will not work as expected.

Type requirements

Template:par req concept

Specializations

Several specializations for common character sequence types are provided:

Defined in header <regex>
Type	Definition
csub_match	sub_match<const char*>
wcsub_match	sub_match<const wchar_t*>
ssub_match	sub_match<std::string::const_iterator>
wssub_match	sub_match<std::wstring::const_iterator>

Member types

Member type	Definition
iterator	BidirIt
value_type	std::iterator_traits<BidirIt>::value_type
difference_type	std::iterator_traits<BidirIt>::difference_type
string_type	std::basic_string<value_type>

Member objects

matched

Indicates if this match was successful.

Inherited from std::pair

first	Start of the match sequence.
second	One-past-the-end of the match sequence.

Member functions

(constructor)	constructs the match object (public member function)
Observers
length	returns the length of the match (if any) (public member function)
stroperator string_type	converts to the underlying string type (public member function)
compare	compares matched subsequence (if any) (public member function)

Non-member functions

Template:cpp/regex/dsc operator cmp

operator<<

outputs the matched character subsequence (function template)

See also

regex_token_iterator (C++11)

iterates through regex submatches (class template)