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CTYPE(2)                      System Calls Manual                     CTYPE(2)



NAME
       isalpha,   isupper,   islower,  isdigit,  isxdigit,  isalnum,  isspace,
       ispunct,  isprint,  isgraph,  iscntrl,  isascii,   toascii,   _toupper,
       _tolower, toupper, tolower - ASCII character classification

SYNOPSIS
       #include <u.h>
       #include <libc.h>
       #include <ctype.h>

       isalpha(c)

       isupper(c)

       islower(c)

       isdigit(c)

       isxdigit(c)

       isalnum(c)

       isspace(c)

       ispunct(c)

       isprint(c)

       isgraph(c)

       iscntrl(c)

       isascii(c)

       _toupper(c)

       _tolower(c)

       toupper(c)

       tolower(c)

       toascii(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 fopen(2).

       isalpha  c is a letter, a-z or A-Z

       isupper  c is an upper case letter, A-Z

       islower  c is a lower case letter, a-z

       isdigit  c is a digit, 0-9

       isxdigit c is a hexadecimal digit, 0-9 or a-f or A-F

       isalnum  c is an alphanumeric character, a-z or A-Z or 0-9

       isspace  c is a space, horizontal tab, newline, vertical tab, formfeed,
                or carriage return (0x20, 0x9, 0xA, 0xB, 0xC, 0xD)

       ispunct  c      is      a     punctuation     character     (one     of
                !"#$%&'()*+,-./:;<=>?@[\]^_`{|}~)

       isprint  c is a printing character, 0x20 (space) through 0x7E (tilde)

       isgraph  c is a visible printing character, 0x21 (exclamation)  through
                0x7E (tilde)

       iscntrl  c  is a delete character, 0x7F, or ordinary control character,
                0x0 through 0x1F

       isascii  c is an ASCII character, 0x0 through 0x7F

       Toascii is not a classification macro;  it  converts  its  argument  to
       ASCII range by anding with 0x7F.

       If c is an upper case letter, tolower returns the lower case version of
       the character; otherwise it returns the original character.  Toupper is
       similar,  returning the upper case version of a character or the origi‐
       nal character.  Tolower and toupper are functions; _tolower and  _toup‐
       per are corresponding macros which should only be used when it is known
       that the argument is upper case or lower case, respectively.

SOURCE
       /sys/include/ctype.h
              for the macros.

       /sys/src/libc/port/ctype.c
              for the tables.

SEE ALSO
       isalpharune(2)

BUGS
       These macros are ASCII-centric.



                                                                      CTYPE(2)