std::regex_replace (3) - Linux Manuals

std::regex_replace: std::regex_replace

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