cpp/locale/ctype char/is

@1@ Checks if the character is classified by the mask  according to the classification table returned by the member function table. Effectively calculates. @2@ For every character in the character array, reads its full classification mask from the classification table returned by the member function table (that is, evaluates and stores it in the corresponding element of the array pointed to by.

If, then an implementation-defined value is substituted instead of , possibly different for different values of.

Return value
@1@ if  is classified by  in,  otherwise @2@