Check if a file exist

 
/* example code to check if a file exists. This function also checks, */
/* if the name is already used by a directory or a device (e.g. CON)  */
/* Note that this routine won't find hidden or system files.          */

  do until fileName = ""
    call charOut, "Enter a filename to check: "
    fileName = lineIN()
    say "The result of FileExist(" || fileName || ") is: " || ,
        FileExist( fileName )                                /* v2.60 */
  end /* do until iLIne = "" */

exit 0

/* ------------------------------------------------------------------ */
/* function: Check if a file exists                                   */
/*                                                                    */
/* call:     FileExist fileToTest                                     */
/*                                                                    */
/* where:    fileToTest - name of the file to test                    */
/*                                                                    */
/* returns:  -2 - invalid parameter                                   */
/*           -1 - cannot detect (e.g. the drive is not ready)         */
/*            0 - neither a file, a device nor a directory with this  */
/*                name exist                                          */
/*            1 - the file exist                                      */
/*            2 - a device driver with the name exists                */
/*            3 - a directory with the name exists                    */
/*                                                                    */
FileExist: PROCEDURE
  parse arg fileName                                         /* v2.90 */

                        /* install temporary error handler            */
  SIGNAL ON NOTREADY NAME FileExistError
  SIGNAL ON FAILURE  NAME FileExistError
  SIGNAL ON ERROR    NAME FileExistError

  thisRC = -2           /* rc = -2 ->> invalid parameter              */

                        /* check the parameter                        */
  if strip( fileName ) <> "" then
  do
    thisRC = -1         /* rc = -1 ->> cannot detect the result       */

                        /* check if the drive with the file is ready  */
    call stream fileName
                        /* turn of some error handling so we can      */
                        /* determine if the given name is the name of */
                        /* a device (for example "LPT1")              */
    SIGNAL OFF NOTREADY

    if stream( fileName, "c", "QUERY EXISTS" ) <> "" then
    do
                        /* seems that the file exists -- check if     */
                        /* it is a device                             */
      if stream( fileName, "c", "QUERY DATETIME" ) == "" then
        thisRC = 2      /* rc = 2 ->> this is a device name           */
      else
        thisRC = 1      /* rc = 1 ->> this is a file name             */
    end /* if stream( ... */
    else
    do
                        /* seems that the file does not exist --      */
                        /* check if a directory with the name for the */
                        /* file exist                                 */

                        /* save the current directory of the current  */
                        /* drive                                      */
      thisDir = directory()
                        /* save the current directory of the drive    */
                        /* with the file to check                     */
      tempDir = directory( fileSpec( "Drive", fileName ) )

      if directory( fileName ) <> "" then
        thisRC = 3      /* rc = 3 ->> a dir with this name exists     */
      else
        thisRC = 0      /* rc = 0 ->> neither a file, a device nor a  */
                        /*            dir with this name exists       */

                        /* restore the current directory of the drive */
                        /* with the directory to check                */
      call directory tempDir
                        /* restore the current directory of the       */
                        /* current drive                              */
      call directory thisDir
    end /* else */
  end /* if strip( fileName ) <> "" then */

FileExistError:

RETURN thisRC