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,
const std::basic_regex<CharT,Traits>& re, (1) (since C++11)
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,
const std::basic_regex<CharT,Traits>& re, (5) (since C++11)
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
fmt - the regex replacement format string, exact syntax depends on the value
of flags
flags - the match flags of type std::regex_constants::match_flag_type
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>)