NAME
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isalpha, isupper, islower, isdigit, isxdigit, isalnum, isspace,
ispunct, isprint, isgraph, iscntrl, isascii, toascii, _toupper,
_tolower, toupper, tolower – ASCII character classification |
SYNOPSIS
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#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)
|
DESCRIPTION
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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). isalphac is a letter, a–z or A–Z isupperc is an upper case letter, A–Z islowerc is a lower case letter, a–z isdigit c is a digit, 0–9 isxdigitc is a hexadecimal digit, 0–9 or a–f or A–F isalnumc is an alphanumeric character, a–z or A–Z or 0–9 isspacec is a space, horizontal tab, newline, vertical tab, formfeed, or carriage return (0x20, 0x9, 0xA, 0xB, 0xC, 0xD) ispunctc is a punctuation character (one of !"#$%&'()*+,–./:;<=>?@[\]^_`{|}~) isprint c is a printing character, 0x20 (space) through 0x7E (tilde) isgraphc 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 original character. Tolower and toupper are functions;
_tolower and _toupper are corresponding macros which should
only be used when it is known that the argument is upper case
or lower case, respectively. |
SOURCE
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/sys/include/ctype.h for the macros. /sys/src/libc/port/ctype.c for the tables. |
SEE ALSO
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isalpharune(2) |
BUGS
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These macros are ASCII–centric. |