28 Regular expressions library [re]

28.11 Regular expression algorithms [re.alg]

28.11.3 regex_search [re.alg.search]

template <class BidirectionalIterator, class Allocator, class charT, class traits> bool regex_search(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);

Requires: Type BidirectionalIterator shall satisfy the requirements of a Bidirectional Iterator ([bidirectional.iterators]).

Effects: Determines whether there is some sub-sequence within [first,last) that matches the regular expression e. The parameter flags is used to control how the expression is matched against the character sequence. Returns true if such a sequence exists, false otherwise.

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 [tab:re:alg:search].

Table 143 — Effects of regex_search algorithm
ElementValue
m.size() 1 + e.mark_count()
m.empty() false
m.prefix().first first
m.prefix().second m[0].first
m.prefix().matched m.prefix().first != m.prefix().second
m.suffix().first m[0].second
m.suffix().second last
m.suffix().matched m.suffix().first != m.suffix().second
m[0].first The start of the sequence of characters that matched the regular expression
m[0].second The end of the sequence of characters that matched the regular expression
m[0].matched true if a match was found, and false otherwise.
m[n].first For all integers 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 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 n < m.size(), true if sub-expression n participated in the match, false otherwise.

template <class charT, class Allocator, class traits> bool regex_search(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);

Returns: The result of regex_search(str, str + char_traits<charT>::length(str), m, e, flags).

template <class ST, class SA, class Allocator, class charT, class traits> bool regex_search(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);

Returns: The result of regex_search(s.begin(), s.end(), m, e, flags).

template <class BidirectionalIterator, class charT, class traits> bool regex_search(BidirectionalIterator first, BidirectionalIterator last, const basic_regex<charT, traits>& e, regex_constants::match_flag_type flags = regex_constants::match_default);

Effects: Behaves “as if” by constructing an object what of type match_results<BidirectionalIterator> and then returning the result of regex_search(first, last, what, e, flags).

template <class charT, class traits> bool regex_search(const charT* str, const basic_regex<charT, traits>& e, regex_constants::match_flag_type flags = regex_constants::match_default);

Returns: regex_search(str, str + char_traits<charT>::length(str), e, flags)

template <class ST, class SA, class charT, class traits> bool regex_search(const basic_string<charT, ST, SA>& s, const basic_regex<charT, traits>& e, regex_constants::match_flag_type flags = regex_constants::match_default);

Returns: regex_search(s.begin(), s.end(), e, flags).