# IOCTL Statement

#### Purpose:

To allow GW-BASIC to send a "control data" string to a character device driver anytime after the driver has been opened.

#### Syntax:

    IOCTL[#]file number,string

#### Comments:

file number is the file number open to the device driver.

string is a valid string expression containing characters that control the device.

IOCTL commands are generally 2 to 3 characters followed by an optional alphanumeric argument. An IOCTL string may be up to 255 bytes long, with commands within the string separated by semicolons.

#### Examples:

If a user had installed a driver to replace lpt1, and that driver was able to set page length (the number of lines to print on a page before issuing a form feed), then the following lines would open the new lpt1 driver and set the page length to 66 lines:

    OPEN "LPT1:" FOR OUTPUT AS #1
    IOCTL #1, "PL66"

The following statements open lpt1 with an initial page length of 56 lines:

    OPEN "\DEV\LPT1" FOR OUTPUT AS #1
    IOCTL #1, "PL56"