NAME
isdigit, isdigit_l
— decimal-digit single-byte
character test
SYNOPSIS
#include
<ctype.h>
int
isdigit(int
c);
int
isdigit_l(int
c, locale_t
locale);
DESCRIPTION
The
isdigit()
and
isdigit_l()
functions test for any decimal-digit character. In the C locale, the
complete list of decimal digits is 0 and 1–9.
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,
different c arguments may correspond to the digits,
and the results of isdigit() may depend on the
LC_CTYPE
locale(1).
SEE ALSO
isalnum(3), isalpha(3), isascii(3), isblank(3), iscntrl(3), isgraph(3), islower(3), isprint(3), ispunct(3), isspace(3), isupper(3), iswdigit(3), isxdigit(3), stdio(3), toascii(3), tolower(3), toupper(3), ascii(7)
STANDARDS
The isdigit() function conforms to
ANSI X3.159-1989 (“ANSI C89”),
and isdigit_l() to IEEE Std
1003.1-2008 (“POSIX.1”).
HISTORY
The isdigit() function first appeared in
Version 7 AT&T UNIX, and
isdigit_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.