#define NOARGC  /* no arg count passing */›#define FIXARGC /* don't expect arg counts passed in */›/*›** return 'true' if c is alphanumeric›*/›isalnum(c) int c; ›$(›  return ((c<='z' && c>='a') ||›          (c<='Z' && c>='A') ||›          (c<='9' && c>='0'));›$)›