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std::ctype<char>::is

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

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.