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Command: isdigit | Section: 3 | Source: OpenBSD | File: isdigit.3
ISDIGIT(3) FreeBSD Library Functions Manual ISDIGIT(3)
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.
FreeBSD 14.1-RELEASE-p8 January 20, 2023 FreeBSD 14.1-RELEASE-p8