The FCLOSE intrinsic is used to terminate access to a file.
It applies to files on all devices and frees any resources that
were assigned at the time the file was opened. If more than one
file is opened against a device, the device itself is not deallocated
until an FCLOSE is issued against every file opened on that device
by your program. The syntax of the FCLOSE call is as follows:
FCLOSE(filenum,disposition,securitycode); |
The filenum parameter contains the
file number of the file to be closed. The disposition
and securitycode parameters provide facilities
for determining file disposition and security levels for files on
devices other than terminals and printers. They are not meaningful
for asynchronous devices and should be set to 0.
Some of the device settings that may have been altered by
FCONTROL (or FDEVICECONTROL) calls issued by your program will be
reset to their default settings at FCLOSE. However, this is not
true for all device settings that may have been altered. You are
responsible for making sure that your program does not adversely
affect the way the device will act after your program terminates.
It is good programming practice to reset any device characteristics
your program alters and to issue an FCLOSE for every file your program
opens.
Should your program fail to issue an FCLOSE for a file it
has opened, the file system will automatically issue an FCLOSE for
that file when the program terminates. When the last file opened
against a device is closed, all device characteristics are returned
to their configured settings. If there is a session associated with
the device, the last file is not closed until the session is terminated.
In Figure 3-10 “Opening a Read Port and a Write Port”, two FCLOSE
calls are issued to close ports previously opened for reading and
writing to a terminal. Condition codes are checked after each FCLOSE
call through the Pascal ccode function,
which will return a value of CCE if no errors occur during the call,
or of CCL or CCG if errors do occur.
Figure 3-10 Opening a Read Port and a Write Port
