CTYPE(2)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 ALSOisalpharune(2)BUGS
These macros are ASCII-centric.
CTYPE(2)