Manual page for CTYPE(3V)
ctype, conv, isalpha, isupper, islower, isdigit, isxdigit, isalnum, isspace, ispunct, isprint, iscntrl, isascii, isgraph, toupper, tolower, toascii - character classification and conversion macros and functions
SYNOPSIS
#include <ctype.h>
isalpha(c)
...
DESCRIPTION
Character Classification Macros
These macros classify
character-coded integer values according to the rules of the coded character
set defined by the character type information in the program's locale
(category
LC_CTYPE).
On program startup the
LC_CTYPE
category of locale is equivalent to the
"C"
locale.
In the
"C"
locale, or in a locale where the character type information is not defined,
characters are classified according to the rules of the
US-ASCII
7-bit coded character set.
The control characters are those below 040 (and the single byte 0177)
(DEL).
See
ascii.7
In all cases that argument is an
int,
the value of which must be representable as an
unsigned char
or must equal the value of the macro
EOF.
If the argument has any other value, the behavior is undefined.
Each is a predicate returning nonzero for true, zero for false.
isascii()
is defined on all integer values.
- isalpha(c)
-
c
is a letter.
- isupper(c)
-
c
is an upper case letter.
- islower(c)
-
c
is a lower case letter.
- isdigit(c)
-
c
is a digit [0-9].
- isxdigit(c)
-
c
is a hexadecimal digit [0-9], [A-F], or [a-f].
- isalnum(c)
-
c
is an alphanumeric character, that is,
c
is a letter or a digit.
- isspace(c)
-
c
is a
SPACE,
TAB,
RETURN,
NEWLINE,
FORMFEED,
or
vertical tab
character.
- ispunct(c)
-
c
is a punctuation character (neither control nor alphanumeric).
- isprint(c)
-
c
is a printing character.
- iscntrl(c)
-
c
is a delete character or ordinary control character.
- isascii(c)
-
c
is an
ASCII
character, code less than 0200.
- isgraph(c)
-
c
is a visible graphic character.
Character Conversion Macros
- toascii(c)
-
Masks
c
with the correct value so that
c
is guaranteed to be an
ASCII
character in the range 0 through 0x7f.
Will not perform mapping from a non-ASCII
coded character set into
ASCII.
Character Conversion Functions
These functions perform simple conversions on single characters.
They replace the previous macro definitions
which did not extend to support variant settings of the
LC_CTYPE
locale category.
- toupper(c)
-
Converts
c
to its upper-case equivalent.
This function works correctly for all coded character sets
and all characters within such sets selected by a valid setting of
the
LC_CTYPE
locale category.
- tolower(c)
-
Converts
c
to its lower-case equivalent.
This function works correctly for all coded character sets
and all characters within such sets selected by a valid setting of
the
LC_CTYPE
locale category.
If the argument to any of these macros is not in the
domain of the function, the result is undefined.
SYSTEM V DESCRIPTION
Character Conversion Macros
The macros
_toupper()
and
_tolower()
are faster than the equivalent functions
(toupper()
and
tolower())
but only work properly on a restricted range of characters, and will not
work on a
LC_CTYPE
category other than the default
"C"
(ASCII).
These macros perform simple conversions on single characters.
- _toupper(c)
-
converts
c
to its upper-case equivalent.
Note:
This
only
works where
c
is known to be a lower-case character to start with (presumably checked
using
islower()).
- _tolower(c)
-
converts
c
to its lower-case equivalent.
Note:
This
only
works where
c
is known to be a upper-case character to start with (presumably checked
using
isupper()).
SEE ALSO
setlocale.3v
ascii.7
iso_8859_1.7
Created by unroff & hp-tools.
© somebody (See intro for details). All Rights Reserved.
Last modified 11/5/97