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std::match_results::format(3)  C++ Standard Libary std::match_results::format(3)

NAME
     std::match_results::format - std::match_results::format

Synopsis
	template< class OutputIt >

	OutputIt format( OutputIt out,
			 const	char_type*  fmt_first, const char_type*      (1)
     (since C++11)
	fmt_last,
			 std::regex_constants::match_flag_type flags =

			     std::regex_constants::format_default ) const;
	template< class OutputIt, class ST, class SA >

	OutputIt format( OutputIt out,
			 const basic_string<char_type,ST,SA>&  fmt,	     (2)
     (since C++11)
			 std::regex_constants::match_flag_type flags =

			     std::regex_constants::format_default ) const;
	template< class ST, class SA >

	std::basic_string<char_type,ST,SA>
	    format(  const  std::basic_string<char_type,ST,SA>& fmt,	     (3)
     (since C++11)
		    std::regex_constants::match_flag_type flags =

			std::regex_constants::format_default ) const;
	string_type format( const char_type* fmt_s,

			    std::regex_constants::match_flag_type flags  =   (4)
     (since C++11)

				std::regex_constants::format_default )
	const;

	format	outputs  a format string, replacing any format specifiers or es-
     cape sequences
	in that string with match data from *this.

	1) The format character sequence is defined  by  the  range  [fmt_first,
     fmt_last). The
	resulting character sequence is copied to out.
	2)  The  format  character sequence is defined by the characters in fmt.
     The resulting
	character sequence is copied to out.
	3,4) The format character sequence is defined by the characters  in  fmt
     and fmt_s
	respectively. The resulting character sequence is copied to a newly con-
     structed
	std::basic_string, which is returned.

	The  flags  bitmask  determines  which	format specifiers and escape se-
     quences are
	recognized.

	The behavior of format is undefined if ready() != true.

Parameters
	fmt_begin, fmt_end - pointers to a range of characters defining the for-
     mat character
			     sequence
	fmt		   - std::basic_string defining the format character se-
     quence
	fmt_s		   -  pointer  to  a  null-terminated  character  string
     defining the
			     format character sequence
	out		    -  iterator that the resulting character sequence is
     copied to
	flags		   - std::regex_constants::match_flag_type bitmask spec-
     ifying which
			     format specifiers and escape sequences  are  recog-
     nized

Type requirements
	-
	OutputIt must meet the requirements of LegacyOutputIterator.

Return value
	1,2) out
	3,4)  The  newly  constructed  string containing resulting character se-
     quence.

Exceptions
	May throw implementation-defined exceptions.

Example
     // Run this code

      #include <iostream>
      #include <regex>
      #include <string>

      int main()
      {
	  std::string s = "for a good time, call 867-5309";
	  std::regex phone_regex("\\d{3}-\\d{4}");
	  std::smatch phone_match;

	  if (std::regex_search(s, phone_match, phone_regex))
	  {
	      std::string fmt_s = phone_match.format(
		  "$`"	 // $` means characters before the match
		  "[$&]" // $& means the matched characters
		  "$'"); // $' means characters following the match
	      std::cout << fmt_s << '\n';
	  }
      }

Output:
      for a good time, call [867-5309]

See also
	regex_replace	replaces occurrences of a regular expression  with  for-
     matted
	(C++11) 	replacement text
			(function template)
	match_flag_type options specific to matching
	(C++11) 	(typedef)

http://cppreference.com 	   2024.06.10	   std::match_results::format(3)
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