ISALNUM(3)

NAME
3.1 `isalnum'--alphanumeric character predicate

SYNOPSIS
     #include <ctype.h>
     int isalnum(int 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.

SEE ALSO
isalnum is part of the library. The full documentation for is maintained as a Texinfo manual. If info and are properly installed at your site, the command

    info

will give you access to the complete manual.