NAME¶

std::ctype::is - std::ctype::is

Synopsis¶

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
overload (2) copied the values from vec into
LWG 28 C++98 table(), corrected
which is the reverse of the intended behavior

See also¶

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

Category:¶

* Todo no example