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/*
FUNCTION
<<isalnum>>, <<isalnum_l>>---alphanumeric character predicate
INDEX
isalnum
INDEX
isalnum_l
SYNOPSIS
#include <ctype.h>
int isalnum(int <[c]>);
#include <ctype.h>
int isalnum_l(int <[c]>, locale_t <[locale]>);
DESCRIPTION
<<isalnum>> is a macro which classifies singlebyte charset values by table
lookup. It is a predicate returning non-zero for alphabetic or
numeric ASCII characters, and <<0>> for other arguments. It is defined
only if <[c]> is representable as an unsigned char or if <[c]> is EOF.
<<isalnum_l>> is like <<isalnum>> but performs the check based on the
locale specified by the locale object locale. If <[locale]> is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
You can use a compiled subroutine instead of the macro definition by
undefining the macro using `<<#undef isalnum>>' or `<<#undef isalnum_l>>'.
RETURNS
<<isalnum>>,<<isalnum_l>> return non-zero if <[c]> is a letter or a digit.
PORTABILITY
<<isalnum>> is ANSI C.
<<isalnum_l>> is POSIX-1.2008.
No OS subroutines are required.
*/
#include <_ansi.h>
#include <ctype.h>
#undef isalnum
int
isalnum (int c)
{
return(__CTYPE_PTR[c+1] & (_U|_L|_N));
}
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