std::match_results(3)

NAME
std::match_results - std::match_results

Synopsis
   Defined in header <regex>
   template<
   class BidirIt, (1) (since C++11)
   class Alloc = std::allocator<std::sub_match<BidirIt>>
   > class match_results;
   namespace pmr {
   template <class BidirIt>
   using match_results = std::match_results<BidirIt, (2) (since C++17)
   std::pmr::polymorphic_allocator<
   std::sub_match<BidirIt>>>;
   }
   The class template std::match_results holds a collection of character sequences that
   represent the result of a regular expression match.
   This is a specialized allocator-aware container. It can only be default created,
   obtained from std::regex_iterator, or modified by std::regex_search or
   std::regex_match. Because std::match_results holds std::sub_matches, each of which
   is a pair of iterators into the original character sequence that was matched, it's
   undefined behavior to examine std::match_results if the original character sequence
   was destroyed or iterators to it were invalidated for other reasons.
   The first sub_match (index 0) contained in a match_result always represents the full
   match within a target sequence made by a regex, and subsequent sub_matches represent
   sub-expression matches corresponding in sequence to the left parenthesis delimiting
   the sub-expression in the regex.
   std::match_results meets the requirements of a AllocatorAwareContainer and of a
   SequenceContainer, except that only copy assignment, move assignment, and operations
   defined for a constant containers are supported, and that the semantics of
   comparison functions are different from those required for a container.

Type requirements
   -
   BidirIt must meet the requirements of LegacyBidirectionalIterator.
   -
   Alloc must meet the requirements of Allocator.

Specializations
   Several specializations for common character sequence types are provided:
   Defined in header <regex>
   Type Definition
   std::cmatch std::match_results<const char*>
   std::wcmatch std::match_results<const wchar_t*>
   std::smatch std::match_results<std::string::const_iterator>
   std::wsmatch std::match_results<std::wstring::const_iterator>
   std::pmr::cmatch (C++17) std::pmr::match_results<const char*>
   std::pmr::wcmatch (C++17) std::pmr::match_results<const wchar_t*>
   std::pmr::smatch (C++17) std::pmr::match_results<std::string::const_iterator>
   std::pmr::wsmatch (C++17) std::pmr::match_results<std::wstring::const_iterator>

Member types
   Member type Definition
   allocator_type Allocator
   value_type std::sub_match<BidirIt>
   const_reference const value_type&
   reference value_type&
   const_iterator implementation defined (depends on the underlying container)
   iterator const_iterator
   difference_type std::iterator_traits<BidirIt>::difference_type
   size_type std::allocator_traits<Alloc>::size_type
   char_type std::iterator_traits<BidirIt>::value_type
   string_type std::basic_string<char_type>

Member functions
   constructor constructs the object
                 (public member function)
   destructor destructs the object
                 (public member function)
   operator= assigns the contents
                 (public member function)
   get_allocator returns the associated allocator
                 (public member function)

State
   ready checks if the results are available
                 (public member function)

Size
   empty checks whether the match was successful
                 (public member function)
   size returns the number of matches in a fully-established result state
                 (public member function)
   max_size returns the maximum possible number of sub-matches
                 (public member function)

Element access
   length returns the length of the particular sub-match
                 (public member function)
                 returns the position of the first character of the particular
   position sub-match
                 (public member function)
   str returns the sequence of characters for the particular sub-match
                 (public member function)
   operator[] returns specified sub-match
                 (public member function)
                 returns sub-sequence between the beginning of the target sequence and
   prefix the beginning of the full match.
                 (public member function)
                 returns sub-sequence between the end of the full match and the end of
   suffix the target sequence
                 (public member function)

Iterators
   begin returns iterator to the beginning of the list of sub-matches
   cbegin (public member function)
   end returns iterator to the end of the list of sub-matches
   cend (public member function)

Format
   format formats match results for output
                 (public member function)

Modifiers
   swap swaps the contents
                 (public member function)

Non-member functions
   operator== lexicographically compares the values in the two match
   operator!= result
   (removed in C++20) (function template)
   std::swap(std::match_results) specializes the std::swap algorithm
   (C++11) (function template)