std::sub_match

C++

Language

Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

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<<

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

- BidirIt must meet the requirements of BidirectionalIterator.

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

bool matched

Indicates if this match was successful (public member object)

Inherited from std::pair

BidirIt first	Start of the match sequence. (public member object)
BidirIt second	One-past-the-end of the match sequence. (public member object)

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

operator==operator!=operator<operator<=operator>operator>=	compares two sub_match objects (function template)
operator<<	outputs the matched character subsequence (function template)

See also

regex_token_iterator (C++11)

iterates through regex submatches (class template)