| Defined in header <regex> | ||
|---|---|---|
template< class BidirIt,
class Alloc, class CharT, class Traits >
bool regex_match( BidirIt first, BidirIt last,
std::match_results<BidirIt,Alloc>& m,
const std::basic_regex<CharT,Traits>& e,
std::regex_constants::match_flag_type flags =
std::regex_constants::match_default ); | (1) | (since C++11) |
template< class BidirIt,
class CharT, class Traits >
bool regex_match( BidirIt first, BidirIt last,
const std::basic_regex<CharT,Traits>& e,
std::regex_constants::match_flag_type flags =
std::regex_constants::match_default ); | (2) | (since C++11) |
template< class CharT, class Alloc, class Traits >
bool regex_match( const CharT* str,
std::match_results<const CharT*,Alloc>& m,
const std::basic_regex<CharT,Traits>& e,
std::regex_constants::match_flag_type flags =
std::regex_constants::match_default ); | (3) | (since C++11) |
template< class STraits, class SAlloc,
class Alloc, class CharT, class Traits >
bool regex_match( const std::basic_string<CharT,STraits,SAlloc>& s,
std::match_results<
typename std::basic_string<CharT,STraits,SAlloc>::const_iterator,
Alloc
>& m,
const std::basic_regex<CharT,Traits>& e,
std::regex_constants::match_flag_type flags =
std::regex_constants::match_default ); | (4) | (since C++11) |
template< class CharT, class Traits >
bool regex_match( const CharT* str,
const std::basic_regex<CharT,Traits>& e,
std::regex_constants::match_flag_type flags =
std::regex_constants::match_default ); | (5) | (since C++11) |
template< class STraits, class SAlloc,
class CharT, class Traits >
bool regex_match( const std::basic_string<CharT, STraits, SAlloc>& s,
const std::basic_regex<CharT,Traits>& e,
std::regex_constants::match_flag_type flags =
std::regex_constants::match_default ); | (6) | (since C++11) |
template< class STraits, class SAlloc,
class Alloc, class CharT, class Traits >
bool regex_match( const std::basic_string<CharT,STraits,SAlloc>&&,
std::match_results<
typename std::basic_string<CharT,STraits,SAlloc>::const_iterator,
Alloc
>&,
const std::basic_regex<CharT,Traits>&,
std::regex_constants::match_flag_type flags =
std::regex_constants::match_default ) = delete; | (7) | (since C++14) |
Determines if the regular expression el matches the given target.
1) Determines if there is a match between the regular expression
e and the entire target character sequence [first,last), taking into account the effect of flags. When determining if there is a match, only potential matches that match the entire character sequence are considered. Match results are returned in m. 2) Behaves as (1) above, omitting the match results.
3) Returns
std::regex_match(str, str + std::char_traits<charT>::length(str), m, e, flags). 4) Returns
std::regex_match(s.begin(), s.end(), m, e, flags). 5) Returns
std::regex_match(str, str + std::char_traits<charT>::length(str), e, flags). 6) Returns
std::regex_match(s.begin(), s.end(), e, flags). 7) The overload 4 is prohibited from accepting temporary strings, otherwise this function populates match_results m with string iterators that become invalid immediately.
Note that regex_match will only successfully match a regular expression to an entire character sequence, whereas std::regex_search will successfully match subsequences.
Parameters
| first, last | - | the target character range to apply the regex to, given as iterators |
| m | - | the match results |
| str | - | the target string, given as a null-terminated C-style string |
| s | - | the target string, given as a std::basic_string |
| e | - | the regular expression |
| flags | - | flags used to determine how the match will be performed |
| Type requirements | ||
- BidirIt must meet the requirements of BidirectionalIterator. | ||
Return value
Returns true if a match exists, false otherwise. In either case, the object m is updated, as follows:
If the match does not exist:
m.ready() == true | |
m.empty() == true | |
m.size() == 0 |
If the match exists:
m.ready() | true |
m.empty() | false |
m.size() | number of marked subexpressions plus 1, that is, 1+e.mark_count() |
m.prefix().first | first |
m.prefix().second | first |
m.prefix().matched | false (the match prefix is empty) |
m.suffix().first | last |
m.suffix().second | last |
m.suffix().matched | false (the match suffix is empty) |
m[0].first | first |
m[0].second | last |
m[0].matched | true (the entire sequence is matched) |
m[n].first | the start of the sequence that matched marked sub-expression n, or last if the subexpression did not participate in the match |
m[n].second | the end of the sequence that matched marked sub-expression n, or last if the subexpression did not participate in the match |
m[n].matched | true if sub-expression n participated in the match, false otherwise |
Example
#include <iostream>
#include <string>
#include <regex>
int main()
{
// Simple regular expression matching
std::string fnames[] = {"foo.txt", "bar.txt", "baz.dat", "zoidberg"};
std::regex txt_regex("[a-z]+\\.txt");
for (const auto &fname : fnames) {
std::cout << fname << ": " << std::regex_match(fname, txt_regex) << '\n';
}
// Extraction of a sub-match
std::regex base_regex("([a-z]+)\\.txt");
std::smatch base_match;
for (const auto &fname : fnames) {
if (std::regex_match(fname, base_match, base_regex)) {
// The first sub_match is the whole string; the next
// sub_match is the first parenthesized expression.
if (base_match.size() == 2) {
std::ssub_match base_sub_match = base_match[1];
std::string base = base_sub_match.str();
std::cout << fname << " has a base of " << base << '\n';
}
}
}
// Extraction of several sub-matches
std::regex pieces_regex("([a-z]+)\\.([a-z]+)");
std::smatch pieces_match;
for (const auto &fname : fnames) {
if (std::regex_match(fname, pieces_match, pieces_regex)) {
std::cout << fname << '\n';
for (size_t i = 0; i < pieces_match.size(); ++i) {
std::ssub_match sub_match = pieces_match[i];
std::string piece = sub_match.str();
std::cout << " submatch " << i << ": " << piece << '\n';
}
}
}
}Output:
foo.txt: 1 bar.txt: 1 baz.dat: 0 zoidberg: 0 foo.txt has a base of foo bar.txt has a base of bar foo.txt submatch 0: foo.txt submatch 1: foo submatch 2: txt bar.txt submatch 0: bar.txt submatch 1: bar submatch 2: txt baz.dat submatch 0: baz.dat submatch 1: baz submatch 2: dat
See also
| (C++11) | regular expression object (class template) |
| (C++11) | identifies one regular expression match, including all sub-expression matches (class template) |
| (C++11) | attempts to match a regular expression to any part of a character sequence (function template) |
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