## ŒHC Hard Copy

The monadic system function ŒHC is used to write hard copy to an output device, usually a printer. The exact implementation of ŒHC depends on the system on which APLX is implemented.

### Available Printers

For Server editions of APLX, up to 9 logical printers may be available. These are defined using the Configure Printer option of the File.. Print.. menu, or may be pre-defined in a resource file. Each logical printer defines the spool queue and type of printer to be used.

Once printers have been set up, they can be used through the Print menu, or through ŒHC. In ŒHC printing, all output to the screen is also sent to the printer, unless screen printing has been switched off using ŒHC 1000.

In APLX for Windows and APLX for MacOS, the operation of ŒHC is similar except that printing always takes place to the currently-selected printer, i.e. the printer last selected using the Print Setup dialog. (You can display this dialog under APL program control using the 'Printer' object class in ŒWI, which also provides alternative and more flexible printing facilities). Thus, only printer 1 can be selected using ŒHC, even though there may be more printers potentially available via the dialog.

### Syntax of ŒHC

The syntax of ŒHC is:

         RESULT „ ŒHC CODE

where CODE defines the operation you want to carry out, and RESULT is usually an error code (see below). 0 always means successful operation.

### ŒHC Function Codes

    1 to 9      Switch on printing to printer number 1 to 9 inclusive
                (only printer 1 valid under MacOS and Windows)

    ¯1 to ¯9    Keep the specified spool file open, but do not write to it.
                This option is useful if you want to ask for input, or display
                progress messages which you do not want to print.

    0           Switch off printing, submit the spool file to the
                printer.

    1000        Suppress screen output, but continue to write to the spool file.
                This option is useful if you want APL output to be printed, but not
                appear on the screen. This option is valid only if printing is
                on. Screen output is reset automatically by ŒHC 0.

    ¯1000       End suppression of screen output.

    99          Return the current value of ŒHC.  In this case, the
                result is not an error code, but a printer number
                1 to 9 (or ¯1 to ¯9), or 0 if printing is not on.

The following codes are valid for Server editions of APLX only:

    100,200...  Open spool file (append if it exists), but don't
                automatically submit on Quad-HC 0.  100 is Printer 1,
                200 is Printer 2, etc.

    101,201...  Submit spool file opened with 100, 200 etc, then delete.

    102,202...  Submit but don't delete.

    103,203...  Delete spool file opened with 100, 200...

### ŒHC Return Codes

    0           Operation successful
    1           Invalid command or printer not defined
    2           Printer not accessible
    3           I/O error or disc full
    4           ŒHC 1000 requested, but printing not on

Topic: APLX Help : Help on APL language : System Functions & Variables : ŒHC Hard Copy

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