isalpha,
isalpha_l —
alphabetic single-byte character test
#include
<ctype.h>
int
isalpha(
int
c);
int
isalpha_l(
int
c,
locale_t
locale);
The
isalpha() and
isalpha_l() functions test whether
c represents a letter.
In the C locale, the complete list of alphabetic characters is A–Z and
a–z.
OpenBSD always uses the C locale for these
functions, ignoring the global locale, the thread-specific locale, and the
locale argument.
These functions return zero if the character tests false or non-zero if the
character tests true.
On systems supporting non-ASCII single-byte character encodings, these functions
may return non-zero for additional characters, and the results of
isalnum() may depend on the
LC_CTYPE
locale(1), but they never return
non-zero for any character for which
iscntrl(3),
isdigit(3),
ispunct(3), or
isspace(3) is true.
isalnum(3),
isascii(3),
isblank(3),
iscntrl(3),
isdigit(3),
isgraph(3),
islower(3),
isprint(3),
ispunct(3),
isspace(3),
isupper(3),
iswalpha(3),
isxdigit(3),
stdio(3),
toascii(3),
tolower(3),
toupper(3),
ascii(7)
The
isalpha() function conforms to
ANSI X3.159-1989
(“ANSI C89”), and
isalpha_l() to
IEEE Std 1003.1-2008
(“POSIX.1”).
The
isalpha() function first appeared in
Version 7 AT&T UNIX, and
isalpha_l() has been available since
OpenBSD 6.2.
The argument
c must be
EOF or representable as an
unsigned char; otherwise, the result is
undefined.
![[OpenBSD]](/openbsd.gif){kind=small}