std::basic_regex - cppreference.com (original) (raw)
| | | | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | ------------- | | template< class CharT, class Traits = std::regex_traits<CharT> > class basic_regex; | | (since C++11) |
The class template basic_regex provides a general framework for holding regular expressions.
Several typedefs for common character types are provided:
| Type | Definition |
| std::regex | std::basic_regex<char> |
| std::wregex | std::basic_regex<wchar_t> |
Contents
- 1 Member types
- 2 Member functions
- 3 Constants
- 4 Non-member functions
- 5 Deduction guides(since C++17)
[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
| (constructor) | constructs the regex object (public member function) [edit] |
|---|---|
| (destructor) | destructs the regex object (public member function) [edit] |
| operator= | assigns the contents (public member function) [edit] |
| assign | assigns the contents (public member function) [edit] |
| Observers | |
| mark_count | returns the number of marked sub-expressions within the regular expression (public member function) [edit] |
| flags | returns the syntax flags (public member function) [edit] |
| Locale | |
| getloc | get locale information (public member function) [edit] |
| imbue | set locale information (public member function) [edit] |
| Modifiers | |
| swap | swaps the contents (public member function) [edit] |
| 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.