Defined in header <regex> | ||
|---|---|---|
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.
-BidirIt must meet the requirements of LegacyBidirectionalIterator. |
Several specializations for common character sequence types are provided:
Defined in header <regex> |
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|---|---|
| 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 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> |
| bool matched | Indicates if this match was successful (public member object) |
| BidirIt first | Start of the match sequence. (public member object) |
| BidirIt second | One-past-the-end of the match sequence. (public member object) |
| 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) |
|
|
(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) |
|
(C++11) | iterates through the specified sub-expressions within all regex matches in a given string or through unmatched substrings (class template) |
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