30 Regular expressions library [re]

30.11 Regular expression algorithms [re.alg]

30.11.2 regex_­match [re.alg.match]

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template<class BidirectionalIterator, class Allocator, class charT, class traits> bool regex_match(BidirectionalIterator first, BidirectionalIterator last, match_results<BidirectionalIterator, Allocator>& m, const basic_regex<charT, traits>& e, regex_constants::match_flag_type flags = regex_constants::match_default);
1
#
Preconditions: BidirectionalIterator meets the Cpp17BidirectionalIterator requirements ([bidirectional.iterators]).
2
#
Effects: Determines whether there is a match between the regular expression e, and all of the character sequence [first, last).
The parameter flags is used to control how the expression is matched against the character sequence.
When determining if there is a match, only potential matches that match the entire character sequence are considered.
Returns true if such a match exists, false otherwise.
[Example
: 
std::regex re("Get|GetValue");
std::cmatch m;
regex_search("GetValue", m, re);        // returns true, and m[0] contains "Get"
regex_match ("GetValue", m, re);        // returns true, and m[0] contains "GetValue"
regex_search("GetValues", m, re);       // returns true, and m[0] contains "Get"
regex_match ("GetValues", m, re);       // returns false
— end example
]
3
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Postconditions: m.ready() == true in all cases.
If the function returns false, then the effect on parameter m is unspecified except that m.size() returns 0 and m.empty() returns true.
Otherwise the effects on parameter m are given in Table 141.
Table 141: Effects of regex_­match algorithm   [tab:re.alg.match]
Element
Value
m.size()
1 + e.mark_­count()
m.empty()
false
m.prefix().first
first
m.prefix().second
first
m.prefix().matched
false
m.suffix().first
last
m.suffix().second
last
m.suffix().matched
false
m[0].first
first
m[0].second
last
m[0].matched
true
m[n].first
For all integers 0 < n < m.size(), the start of the sequence that matched sub-expression n.
Alternatively, if sub-expression n did not participate in the match, then last.
m[n].second
For all integers 0 < n < m.size(), the end of the sequence that matched sub-expression n.
Alternatively, if sub-expression n did not participate in the match, then last.
m[n].matched
For all integers 0 < n < m.size(), true if sub-expression n participated in the match, false otherwise.
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template<class BidirectionalIterator, class charT, class traits> bool regex_match(BidirectionalIterator first, BidirectionalIterator last, const basic_regex<charT, traits>& e, regex_constants::match_flag_type flags = regex_constants::match_default);
4
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Effects: Behaves “as if” by constructing an instance of match_­results<BidirectionalIterator> what, and then returning the result of regex_­match(first, last, what, e, flags).
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template<class charT, class Allocator, class traits> bool regex_match(const charT* str, match_results<const charT*, Allocator>& m, const basic_regex<charT, traits>& e, regex_constants::match_flag_type flags = regex_constants::match_default);
5
#
Returns: regex_­match(str, str + char_­traits<charT>​::​length(str), m, e, flags).
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template<class ST, class SA, class Allocator, class charT, class traits> bool regex_match(const basic_string<charT, ST, SA>& s, match_results<typename basic_string<charT, ST, SA>::const_iterator, Allocator>& m, const basic_regex<charT, traits>& e, regex_constants::match_flag_type flags = regex_constants::match_default);
6
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Returns: regex_­match(s.begin(), s.end(), m, e, flags).
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template<class charT, class traits> bool regex_match(const charT* str, const basic_regex<charT, traits>& e, regex_constants::match_flag_type flags = regex_constants::match_default);
7
#
Returns: regex_­match(str, str + char_­traits<charT>​::​length(str), e, flags)
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template<class ST, class SA, class charT, class traits> bool regex_match(const basic_string<charT, ST, SA>& s, const basic_regex<charT, traits>& e, regex_constants::match_flag_type flags = regex_constants::match_default);
8
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Returns: regex_­match(s.begin(), s.end(), e, flags).