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/*

FUNCTION

        <<isalnum>>---alphanumeric character predicate

INDEX

        isalnum

ANSI_SYNOPSIS

        #include <ctype.h>

        int isalnum(int <[c]>);

TRAD_SYNOPSIS

        #include <ctype.h>

        int isalnum(<[c]>);

DESCRIPTION

<<isalnum>> is a macro which classifies ASCII integer 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

for all integer values.

You can use a compiled subroutine instead of the macro definition by

undefining the macro using `<<#undef isalnum>>'.

RETURNS

<<isalnum>> returns non-zero if <[c]> is a letter (<<a>>--<<z>> or

<<A>>--<<Z>>) or a digit (<<0>>--<<9>>).

PORTABILITY

<<isalnum>> is ANSI C.

No OS subroutines are required.

*/

#include <_ansi.h>

#include <ctype.h>

#undef isalnum

int

_DEFUN(isalnum,(c),int c)

{

        return(__ctype_ptr__[c+1] & (_U|_L|_N));

}