std::sub_match - cppreference.com (original) (raw)
| | | | | -------------------------------------------- | | ------------- | | 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.
Contents
[edit] Type requirements
[edit] Specializations
Several specializations for common character sequence types are provided:
| Defined in header | |
|---|---|
| Type | Definition |
| std::csub_match | std::sub_match<const char*> |
| std::wcsub_match | std::sub_match<const wchar_t*> |
| std::ssub_match | std::sub_matchstd:🧵:const\_iterator\ |
| std::wssub_match | std::sub_matchstd::wstring::const\_iterator\ |
[edit] Nested types
[edit] Data members
| Member | Description |
|---|---|
| whether this match was successful (public member object) |
Inherited from std::pair
| | start of the match sequence (public member object) | | ---------------------------------------------------------------- | | | one-past-the-end of the match sequence (public member object) |
[edit] Member functions
| (constructor) | constructs the match object (public member function) [edit] |
|---|---|
| Observers | |
| length | returns the length of the match (if any) (public member function) [edit] |
| stroperator string_type | converts to the underlying string type (public member function) [edit] |
| compare | compares matched subsequence (if any) (public member function) [edit] |
| Modifiers | |
| swap | swaps the contents (public member function) [edit] |
[edit] Non-member functions
[edit] Example
#include #include #include #include  int main() { std::string sentence{"Friday the thirteenth."}; const std::regex re{"([A-z]+) ([a-z]+) ([a-z]+)"}; std::smatch words; std::regex_search(sentence, words, re); std::cout << std::boolalpha; for (const auto& m : words) { assert(m.matched); std::cout << "m: [" << m << "], m.length(): " << m.length() << ", " "*m.first: '" << *m.first << "', " "*m.second: '" << *m.second << "'\n"; } }
Output:
m: [Friday the thirteenth], m.length(): 21, *m.first: 'F', *m.second: '.' m: [Friday], m.length(): 6, *m.first: 'F', *m.second: ' ' m: [the], m.length(): 3, *m.first: 't', *m.second: ' ' m: [thirteenth], m.length(): 10, *m.first: 't', *m.second: '.'
[edit] See also
| | iterates through the specified sub-expressions within all regex matches in a given string or through unmatched substrings (class template) [edit] | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |