NAME
isdigit, isnumber —
decimal-digit character test
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include
<ctype.h>
int
isdigit(int
c);
int
isnumber(int
c);
DESCRIPTION
The
isdigit()
function tests for a decimal digit character. Regardless of locale, this
includes the following characters only:
| ``0''``1''``2''``3''``4'' |
| ``5''``6''``7''``8''``9'' |
The
isnumber()
function behaves similarly to isdigit(), but may
recognize additional characters, depending on the current locale
setting.
The value of the argument must be representable as an
unsigned char or the value of
EOF.
RETURN VALUES
The isdigit() and
isnumber() functions return zero if the character
tests false and return non-zero if the character tests true.
COMPATIBILITY
The 4.4BSD extension of accepting
arguments outside of the range of the unsigned char
type in locales with large character sets is considered obsolete and may not
be supported in future releases. The iswdigit()
function should be used instead.
SEE ALSO
STANDARDS
The isdigit() function conforms to
ISO/IEC 9899:1990
(“ISO C90”).
HISTORY
The isnumber() function appeared in
4.4BSD.