C++ In a Nutshell

Name

ctype_base class — Base class for ctype facet

Synopsis

class ctype_base{
public:
  enum mask {
    space, print, cntrl, upper, lower, alpha, digit, punct, xdigit,
    alnum=alpha|digit, graph=alnum|punct
  };
};

The ctype_base class is the base class for the ctype and ctype_byname class templates. It declares the mask enumerated type, which is used for classifying characters. Table 13-20 describes the mask literals and their definitions for the classic "C" locale.

Table 13-20. mask literals for classifying characters

Literal	Description	“C” locale
alpha	Alphabetic (a letter)	lower or upper
alnum	Alphanumeric (letter or digit)	alpha or digit
cntrl	Control (nonprintable)	Not print
digit	'0'-'9'	All locales
graph	Character that occupies graphical space	print but not space
lower	Lowercase letter	'a'-'z'
print	Printable character (alphanumeric, punctuation, space, etc.)	Depends on character set; in ASCII: '\x20'-'\x7e')
space	Whitespace	' ', '\f', '\n', '\r', '\t', '\v'
upper	Uppercase letter	'A'-'Z'
xdigit	Hexadecimal digit ('0'-'9', 'a'-'f', 'A'-'F')	All locales

See Also

ctype class template, ctype_byname class template