isdigit
[decimal digit predicate]
SYNOPSIS
#include
<ctype.h>
int isdigit(int
c);
DESCRIPTION
isdigit
is a macro which classifies ASCII integer
values by table lookup. It is a predicate returning non-zero for decimal
digits, and 0 for other characters. It is defined only when isascii(c)
is true or c
is EOF.
You can use a compiled subroutine instead of the macro definition by undefining the macro, using #undef isdigit.
RETURNS
isdigit
returns non-zero if c
is a decimal digit (0–9).
COMPLIANCE
isdigit
is ANSI C.
No supporting OS subroutines are required.
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