v7 man page for ctype

CTYPE(3)						     Library Functions Manual							  CTYPE(3)

NAME
       isalpha, isupper, islower, isdigit, isalnum, isspace, ispunct, isprint, iscntrl, isascii - character classification

SYNOPSIS
       #include <ctype.h>

       isalpha(c)

       . . .

DESCRIPTION
       These macros classify ASCII-coded integer values by table lookup.  Each is a predicate returning nonzero for true, zero for false.  Isascii
       is defined on all integer values; the rest are defined only where isascii is true and on the single non-ASCII value EOF (see stdio(3)).

       isalpha	      c is a letter

       isupper	      c is an upper case letter

       islower	      c is a lower case letter

       isdigit	      c is a digit

       isalnum	      c is an alphanumeric character

       isspace	      c is a space, tab, carriage return, newline, or formfeed

       ispunct	      c is a punctuation character (neither control nor alphanumeric)

       isprint	      c is a printing character, code 040(8) (space) through 0176 (tilde)

       iscntrl	      c is a delete character (0177) or ordinary control character (less than 040).

       isascii	      c is an ASCII character, code less than 0200

SEE ALSO
       ascii(7)

																	  CTYPE(3)