CTYPE
Section: C Library Functions (3)
Updated: May 12, 1986
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NAME
isalpha, isupper, islower, isdigit, isxdigit, isalnum, isspace, ispunct, isprint, isgraph, iscntrl, isascii, toupper, tolower, toascii - character classification macros
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
and
toascii
are defined on all integer values; the rest
are defined only where
isascii
is true and on the single non-ASCII value
EOF (see
stdio(3S)).
- isalpha
-
c
is a letter
- isupper
-
c
is an upper case letter
- islower
-
c
is a lower case letter
- isdigit
-
c
is a digit
- isxdigit
-
c
is a hex digit
- isalnum
-
c
is an alphanumeric character
- isspace
-
c
is a space, tab, carriage return, newline, vertical tab, 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)
- isgraph
-
c
is a printing character, similar to
isprint
except false for space.
- iscntrl
-
c
is a delete character (0177) or ordinary control character
(less than 040).
- isascii
-
c
is an ASCII character, code less than 0200
- tolower
-
c
is converted to lower case. Return value is undefined if not
isupper(c).
- toupper
-
c
is converted to upper case. Return value is undefined if not
islower(c).
- toascii
-
c
is converted to be a valid ascii character.
SEE ALSO
ascii(7)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- SEE ALSO
-
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