template< class ForwardIt >
char_class_type lookup_classname( ForwardIt first,
If the character sequence
[first, last) represents the name of a valid character class in the currently imbued locale (that is, the string between
:] in POSIX regular expressions), returns the implementation-defined value representing this character class. Otherwise, returns zero.
If the parameter
icase is true, the character class ignores character case, e.g. the regex
[:lower:] with std::regex_constants::icase generates a call to
[first, last) indicating the string "lower" and icase == true. This call returns the same bitmask as the call generated by the regex
[:alpha:] with icase == false.
The following character classes are always recognized, in both narrow and wide character forms, and the classifications returned (with icase == false) correspond to the matching classifications obtained by the std::ctype facet of the imbued locale, as follows:
|character class||std::ctype classification|
|"w"||std::ctype_base::alnum with '_' optionally added|
The classification returned for the string "w" may be exactly the same as "alnum", in which case isctype() adds '_' explicitly.
|first, last||-||a pair of iterators which determines the sequence of characters that represents a name of a character class|
|icase||-||if true, ignores the upper/lower case distinction in the character classification|
The bitmask representing the character classification determined by the given character class, or zero if the class is unknown.
|This section is incomplete|
Reason: no example
| indicates membership in a character class |
(public member function)