NAME
isalpha, isalpha_l
— alphabetic single-byte
character test
SYNOPSIS
#include
<ctype.h>
int
isalpha(int
c);
int
isalpha_l(int
c, locale_t
locale);
DESCRIPTION
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.
RETURN VALUES
These functions return zero if the character tests false or non-zero if the character tests true.
ENVIRONMENT
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.
SEE ALSO
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)
STANDARDS
The isalpha() function conforms to
ANSI X3.159-1989 (“ANSI C89”),
and isalpha_l() to IEEE Std
1003.1-2008 (“POSIX.1”).
HISTORY
The isalpha() function first appeared in
Version 7 AT&T UNIX, and
isalpha_l() has been available since
OpenBSD 6.2.
CAVEATS
The argument c must be
EOF or representable as an unsigned
char; otherwise, the result is undefined.