std::regex_replace(3)

NAME
std::regex_replace - std::regex_replace

Synopsis
   Defined in header <regex>
   template< class OutputIt, class BidirIt,
   class Traits, class CharT,
   class STraits, class SAlloc >
   OutputIt regex_replace( OutputIt out, BidirIt first, BidirIt last, (1) (since C++11)
   const std::basic_regex<CharT,Traits>& re,
   const std::basic_string<CharT,STraits,SAlloc>& fmt,
   std::regex_constants::match_flag_type flags =
   std::regex_constants::match_default );
   template< class OutputIt, class BidirIt,
   class Traits, class CharT >
   OutputIt regex_replace( OutputIt out, BidirIt first, BidirIt last,
   const std::basic_regex<CharT,Traits>& re, (2) (since C++11)
   const CharT* fmt,
   std::regex_constants::match_flag_type flags =
   std::regex_constants::match_default );
   template< class Traits, class CharT,
   class STraits, class SAlloc,
   class FTraits, class FAlloc >
   std::basic_string<CharT,STraits,SAlloc>
   regex_replace( const std::basic_string<CharT,STraits,SAlloc>& s, (3) (since C++11)
   const std::basic_regex<CharT,Traits>& re,
   const std::basic_string<CharT,FTraits,FAlloc>& fmt,
   std::regex_constants::match_flag_type flags =
   std::regex_constants::match_default );
   template< class Traits, class CharT,
   class STraits, class SAlloc >
   std::basic_string<CharT,STraits,SAlloc>
   regex_replace( const std::basic_string<CharT,STraits,SAlloc>& s, (4) (since C++11)
   const std::basic_regex<CharT,Traits>& re,
   const CharT* fmt,
   std::regex_constants::match_flag_type flags =
   std::regex_constants::match_default );
   template< class Traits, class CharT,
   class STraits, class SAlloc >
   std::basic_string<CharT>
   regex_replace( const CharT* s, (5) (since C++11)
   const std::basic_regex<CharT,Traits>& re,
   const std::basic_string<CharT,STraits,SAlloc>& fmt,
   std::regex_constants::match_flag_type flags =
   std::regex_constants::match_default );
   template< class Traits, class CharT >
   std::basic_string<CharT>
   regex_replace( const CharT* s,
   const std::basic_regex<CharT,Traits>& re, (6) (since C++11)
   const CharT* fmt,
   std::regex_constants::match_flag_type flags =
   std::regex_constants::match_default );
   regex_replace uses a regular expression to perform substitution on a sequence of
   characters:
   1) Copies characters in the range [first,last) to out, replacing any sequences that
   match re with characters formatted by fmt. In other words:
                        * Constructs a std::regex_iterator object i as if by
                        std::regex_iterator<BidirIt, CharT, traits> i(first, last,
                        re, flags), and uses it to step through every match of re
                        within the sequence [first,last).
                        * For each such match m, copies the non-matched subsequence
                        (m.prefix()) into out as if by out =
                        std::copy(m.prefix().first, m.prefix().second, out) and
                        then replaces the matched subsequence with the formatted
                        replacement string as if by calling out = m.format(out,
                        fmt, flags).
                        * When no more matches are found, copies the remaining
                        non-matched characters to out as if by out =
                        std::copy(last_m.suffix().first, last_m.suffix().second,
                        out) where last_m is a copy of the last match found.
                        * If there are no matches, copies the entire sequence into
                        out as-is, by out = std::copy(first, last, out)
                        * If flags contains std::regex_constants::format_no_copy,
                        the non-matched subsequences are not copied into out.
                        * If flags contains std::regex_constants::format_first_only,
                        only the first match is replaced.
   2) same as 1), but the formatted replacement is performed as if by calling out =
   m.format(out, fmt, fmt + char_traits<charT>::length(fmt), flags)
   3-4) Constructs an empty string result of type std::basic_string<CharT, ST, SA> and
   calls std::regex_replace(std::back_inserter(result), s.begin(), s.end(), re, fmt,
   flags).
   5-6) Constructs an empty string result of type std::basic_string<CharT> and calls
   std::regex_replace(std::back_inserter(result), s, s +
   std::char_traits<CharT>::length(s), re, fmt, flags).

Parameters
   first, last - the input character sequence, represented as a pair of iterators
   s - the input character sequence, represented as std::basic_string or
                 character array
   re - the std::basic_regex that will be matched against the input sequence
   flags - the match flags of type std::regex_constants::match_flag_type
   fmt - the regex replacement format string, exact syntax depends on the value
                 of flags
   out - output iterator to store the result of the replacement

Type requirements
   -
   OutputIt must meet the requirements of LegacyOutputIterator.
   -
   BidirIt must meet the requirements of LegacyBidirectionalIterator.

Return value
   1-2) Returns a copy of the output iterator out after all the insertions.
   3-6) Returns the string result which contains the output.

Exceptions
   May throw std::regex_error to indicate an error condition.

Example
// Run this code
 #include <iostream>
 #include <iterator>
 #include <regex>
 #include <string>
 int main()
 {
    std::string text = "Quick brown fox";
    std::regex vowel_re("a|e|i|o|u");
    // write the results to an output iterator
    std::regex_replace(std::ostreambuf_iterator<char>(std::cout),
                       text.begin(), text.end(), vowel_re, "*");
    // construct a string holding the results
    std::cout << '\n' << std::regex_replace(text, vowel_re, "[$&]") << '\n';
 }

Output:
 Q**ck br*wn f*x
 Q[u][i]ck br[o]wn f[o]x

See also
   regex_search attempts to match a regular expression to any part of a character
   (C++11) sequence
                   (function template)
   match_flag_type options specific to matching
   (C++11) (typedef)
                   replaces specified portion of a string
   replace (public member function of
                   std::basic_string<CharT,Traits,Allocator>)