std::sub_match
| Defined in header <regex>
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| template<class BidirIt> class sub_match; |
(since C++11) | |
The class template std::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 std::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.
std::sub_match inherits from std::pair<BidirIt, BidirIt>, although it cannot be treated as a std::pair object because member functions such as assignment will not work as expected.
Type requirements
-BidirIt must meet the requirements of LegacyBidirectionalIterator.
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Specializations
Several specializations for common character sequence types are provided:
| Defined in header
<regex> | |
| Type | Definition |
std::csub_match
|
std::sub_match<const char*> |
std::wcsub_match
|
std::sub_match<const wchar_t*> |
std::ssub_match
|
std::sub_match<std::string::const_iterator> |
std::wssub_match
|
std::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
| This section is incomplete Reason: Apply LWG 3204, add the swap() member function |
| constructs the match object (public member function) | |
Observers | |
| returns the length of the match (if any) (public member function) | |
| converts to the underlying string type (public member function) | |
| compares matched subsequence (if any) (public member function) | |
Non-member functions
| (removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(C++20) |
compares a sub_match with another sub_match, a string, or a character (function template) |
| outputs the matched character subsequence (function template) |
See also
| (C++11) |
iterates through the specified sub-expressions within all regex matches in a given string or through unmatched substrings (class template) |