< cpp‎ | locale‎ | ctype char
Defined in header <locale>
bool is( mask m, char c ) const;
const char* is( const char* low, const char* high, mask* vec ) const;
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 [lowhigh), 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.


[edit] 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

[edit] Return value

1) true if c is classified by m in table(), false otherwise.
2) high

[edit] 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.

[edit] Example

[edit] 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

[edit] See also

classifies a character or a character sequence
(virtual protected member function of std::ctype<CharT>) [edit]