std::regex_match

Parameters

s

A string with the target sequence (the subject) against which the regex expression is matched.

rgx

A basic_regex object (the pattern) to match.

flags

Flags used to control how rgx is matched.
One or more of these constants can be combined (using the bitwise OR operator, |) to form a valid bitmask value of type regex_constants::match_flag_type:

flag*	effects on match	notes
match_default	Default	Default matching behavior. This constant has a value of zero**.
match_not_bol	Not Beginning-Of-Line	The first character is not considered a beginning of line ("^" does not match).
match_not_eol	Not End-Of-Line	The last character is not considered an end of line ("$" does not match).
match_not_bow	Not Beginning-Of-Word	The escape sequence "\b" does not match as a beginning-of-word.
match_not_eow	Not End-Of-Word	The escape sequence "\b" does not match as an end-of-word.
match_any	Any match	Any match is acceptable if more than one match is possible.
match_not_null	Not null	Empty sequences do not match.
match_continuous	Continuous	The expression must match a sub-sequence that begins at the first character. Sub-sequences must begin at the first character to match.
match_prev_avail	Previous Available	One or more characters exist before the first one. (match_not_bol and match_not_bow are ignored)
format_default	Default	Same as match_default. This constant has a value of zero**.
format_sed	None	Ignored by this function. See regex_constants for more info.
format_no_copy
format_first_only

* These bitmask flag names are available under the std::regex_constants namespace (see regex_constants for more details).
** Constants with a value of zero are ignored if some other flag is set.
match_flag_type is a type available under the std::regex_constants namespace.

first, last

Bidirectional iterators to the initial and final positions in the range of characters used as target sequence for the match. The range used is [first,last), which includes all the characters between first and last, including the character pointed by first but not the character pointed by last.
The function template type can be any type of bidirectional iterator to characters.

m

Object of a match_results type (such as cmatch or smatch) that is filled by this function with information about the match results and any submatches found.
The type of the match_results object shall be instantiated with the appropriate iterator type to iterate through the characters in the character sequence s (or between begin and end).

Return value

Example

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// regex_match example
#include <iostream>
#include <string>
#include <regex>

int main ()
{

  if (std::regex_match ("subject", std::regex("(sub)(.*)") ))
    std::cout << "string literal matched\n";

  const char cstr[] = "subject";
  std::string s ("subject");
  std::regex e ("(sub)(.*)");

  if (std::regex_match (s,e))
    std::cout << "string object matched\n";

  if ( std::regex_match ( s.begin(), s.end(), e ) )
    std::cout << "range matched\n";

  std::cmatch cm;    // same as std::match_results<const char*> cm;
  std::regex_match (cstr,cm,e);
  std::cout << "string literal with " << cm.size() << " matches\n";

  std::smatch sm;    // same as std::match_results<string::const_iterator> sm;
  std::regex_match (s,sm,e);
  std::cout << "string object with " << sm.size() << " matches\n";

  std::regex_match ( s.cbegin(), s.cend(), sm, e);
  std::cout << "range with " << sm.size() << " matches\n";

  // using explicit flags:
  std::regex_match ( cstr, cm, e, std::regex_constants::match_default );

  std::cout << "the matches were: ";
  for (unsigned i=0; i<cm.size(); ++i) {
    std::cout << "[" << cm[i] << "] ";
  }

  std::cout << std::endl;

  return 0;
}

string literal matched
string object matched
range matched
string literal with 3 matches
string object with 3 matches
range with 3 matches
the matches were: [subject] [sub] [ject]

See also

regex_search

Search sequence (function template)

regex_replace

Replace matched sequence (function template)

regex_iterator

Regex iterator (class template)

match_results

Match results (class template)