Character Test Macros

	int isalnum( int c )	- nonzero if letter or digit
	int isalpha( int c )	- nonzero if letter
	int isascii( int c )	- nonzero if in range 0-127
	int iscntrl( int c )	- nonzero if 0x7F, or 0x00-0x1F
	int isdigit( int c )	- nonzero if digit
	int isgraph( int c )	- nonzero if printable 0x21-0x7E excl space
	int islower( int c )	- nonzero if lowercase
	int isprint( int c )	- nonzero if printable 0x20-0x7E
	int ispunct( int c )	- nonzero if punct char (iscntrl | isspace)
	int isspace( int c )	- nonzero if space,tab, CR, LF, VT or FF
	int isupper( int c )	- nonzero if uppercase
	int isxdigit( int c )	- nonzero if hexadecimal digit
	    

	- prototype in ctype.h