std::basic_regex
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Regular expressions library
Classes
basic_regex
(C++11)
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std::basic_regex
Defined in header
<regex>
template<
(since C++11)
class CharT,
class Traits = std::regex_traits <CharT>
The class template basic_regex provides a general framework for holding regular expressions.
Several typedefs for common character types are provided:
Defined in header
<regex> Type
Definition
std::regex
std::basic_regex<char>
std::wregex
std::basic_regex<wchar_t>
Contents
[edit] Member types
Member type
Definition
value_type
CharT
traits_type
Traits
string_type
Traits::string_type
locale_type
Traits::locale_type
flag_type
std::regex_constants::syntax_option_type
[edit] Member functions
Observers
returns the number of marked sub-expressions within the regular expression
(public member function) [edit]
(public member function) [edit]
Locale
Modifiers
Constants
Grammar option
Effect(s)
ECMAScript
Use the Modified ECMAScript regular expression grammar.
basic
Use the basic POSIX regular expression grammar (grammar documentation).
extended
Use the extended POSIX regular expression grammar (grammar documentation).
awk
Use the regular expression grammar used by the awk utility in POSIX (grammar documentation).
grep
Use the regular expression grammar used by the grep utility in POSIX. This is effectively the same as the basic option with the addition of newline '\n' as an alternation separator.
egrep
Use the regular expression grammar used by the grep utility, with the -E option, in POSIX. This is effectively the same as the extended option with the addition of newline '\n' as an alternation separator in addition to '|'.
Grammar variation
Effect(s)
icase
Character matching should be performed without regard to case.
nosubs
When performing matches, all marked sub-expressions (expr) are treated as non-marking sub-expressions (?:expr). No matches are stored in the supplied std::regex_match structure and mark_count() is zero.
optimize
Instructs the regular expression engine to make matching faster, with the potential cost of making construction slower. For example, this might mean converting a non-deterministic FSA to a deterministic FSA.
collate
Character ranges of the form "[a-b]" will be locale sensitive.
multiline (C++17)
Specifies that ^ shall match the beginning of a line and $ shall match the end of a line, if the ECMAScript engine is selected.
At most one grammar option can be chosen out of ECMAScript, basic, extended, awk, grep, egrep. If no grammar is chosen, ECMAScript is assumed to be selected. The other options serve as variations, such that std::regex("meow", std::regex::icase) is equivalent to std::regex("meow", std::regex::ECMAScript|std::regex::icase).
The member constants in basic_regex are duplicates of the syntax_option_type constants defined in the namespace std::regex_constants.