null

               NULL
      
               См. также tmpfile.
            
               Пример:
            
            #include <stdio.h>
            
            main ()
            {
            char *name1, *name2;
            
            if ((name1 = tmpnam(NULL)) != NULL)
               printf("%s is safe to use as a temporary file.\n",
                      name1);
            else
               printf("cannot create a unique file name\n");
            
            if ((name2 = tempnam("a:\\tmp", "stq")) != NULL)
               printf("%s is safe to use as a temporary file.\n",
                      name2);
            else
               printf("cannot create a unique file name\n");
            }.