public member function
<regex>
bool isctype ( char_type c, char_class_type f ) const;
Check if character is of a class type
Returns true if character c belongs to the character class selected in f.
The character class f is a value returned by regex_traits::lookup_classname or a bitwise OR combination of more than one of these values.
For the standard regex_traits, the function returns the same as calling ctype::is facet with the appropriate mask for the character class f (notice that f is not necessarily the same bitmask type used by ctype::is, in which case the appropriate translation is done before the call), adjusting the result if the character class is broader (such as in "w" and "blank").
This function is called when a regular expression needs to match a character class against a character.
Parameters
- c
- A character.
char_type is a member type, alias of the character type. In regex_traits it is an alias of its template parameter (charT).
- f
- A bitmask value to select character classes.
char_class_type is a member type, defined as the bitmask type returned by regex_traits::lookup_classname.
Return value
true if c belongs to class f, and false otherwise.