IS_OPEN: Checking whether a channel is open

Purpose

As can be seen from the set_windows procedure in the example programs (see the comment in the example 1, you will sometimes need to know whether a channel is open or not. This function can tell you whether a channel is open or not.

Syntax

The syntax of this command is quite simple:

result%=IS_OPEN(#chan%)

where result% is 1 if the channel is open, 0 if not.

Example

         result%=IS_open(#0)

this tells us if channel 0 is open or not. Please note that the '#' is necessary! If you leave it out, or leave out the channel altogther, the function automatically checks channel 0.
PROGS, Professional & Graphical Software
last edited 1996 Aug 06 (wl)