std::ctype<char>::is
From cppreference.com
< cpp | locale | ctype char
| Defined in header <locale>
|
||
| bool is( mask m, char c ) const; |
(1) | |
| const char* is( const char* low, const char* high, mask* vec ) const; |
(2) | |
1) Checks if the character c is classified by the mask m according to the classification table returned by the member function table(). Effectively calculates table()[(unsigned char)c] & m.
2) For every character in the character array
[low, high), reads its full classification mask from the classification table returned by the member function table() (that is, evaluates table()[(unsigned char)*p] and stores it in the corresponding element of the array pointed to by vec.If (unsigned char)c >= std::ctype<char>::table_size, then an implementation-defined value is substituted instead of table()[(unsigned char)c], possibly different for different values of c.
Parameters
| c | - | character to classify |
| m | - | mask to use for classifying a single character |
| low | - | pointer to the first character in an array of characters to classify |
| high | - | one past the end pointer for the array of characters to classify |
| vec | - | pointer to the first element of the array of masks to fill |
Return value
1) true if c is classified by m in table(), false otherwise
2) high
Notes
Unlike the primary template std::ctype, this specialization does not perform a virtual function call when classifying characters. To customize the behavior, a derived class may provide a non-default classification table to the base class constructor.
Example
| This section is incomplete Reason: no example |
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 28 | C++98 | overload (2) copied the values from vec into table(), which is the reverse of the intended behavior |
corrected |
See also
| [virtual] |
classifies a character or a character sequence (virtual protected member function of std::ctype<CharT>) |