NAME¶

std::sub_match - std::sub_match

Synopsis¶

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

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 LegacyBidirectionalIterator.

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)
str converts to the underlying string type
operator string_type (public member function)
compare compares matched subsequence (if any)
(public member function)

Non-member functions¶

operator==
operator!=
operator<
operator<=
operator>
operator>= compares a sub_match with another sub_match, a string, or a
operator<=> character
(removed in C++20) (function template)
(removed in C++20)
(removed in C++20)
(removed in C++20)
(removed in C++20)
(C++20)
operator<< outputs the matched character subsequence
(function template)

See also¶

regex_token_iterator iterates through the specified sub-expressions within all regex
(C++11) matches in a given string or through unmatched substrings
(class template)