Jane.doe at 05:12, 6 April 2023

2023-04-06T05:12:58Z

← Older revision		Revision as of 05:12, 6 April 2023
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	==devclass==		==devclass==

	Specifies the device class for which F$DEVICE is to search. Specify the devclass argument as a character string expression that corresponds to a valid device class name~~. See the DVI$_DEVCLASS item in the $GETDVI system service for additional information.~~		Specifies the device class for which F$DEVICE is to search. Specify the devclass argument as a character string expression that corresponds to a valid device class name:
			* DISK Disk device
			* TAPE Tape device
			* SCOM Synchronous communications device
			* CARD Card reader
			* TERM Terminal
			* LP Line printer
			* REALTIME Real-time
			* MAILBOX Mailbox
			* MISC Miscellaneous device

	==devtype==		==devtype==

Darya.zelenina: Created page with "'''F$DEVICE''' is a lexical function that returns the device names of all devices on a system that meet the specified selection criteria. Note that the d..."

2019-06-28T18:43:10Z

Created page with "'''F$DEVICE''' is a lexical function that returns the device names of all devices on a system that meet the specified selection criteria. Note that the d..."

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'''F$DEVICE''' is a [[Lexical functions|lexical function]] that returns the device names of all devices on a system that meet the specified selection criteria. Note that the device names are returned in random order.

=Syntax=

F$DEVICE([search_devnam],[devclass],[devtype], [stream-id])

=Return Value=

A character string containing the name of a device in the system's list of devices. After the last device name in the system's device list is returned, the F$DEVICE function returns a null string ("").

=Arguments=

==search_devnam==

Specifies the name of the device for which F$DEVICE is to search. The asterisk (*) and the percent sign (%) wildcard characters are allowed in the search_devnam argument. Specify the search_devnam argument as a character string expression.

==devclass==

Specifies the device class for which F$DEVICE is to search. Specify the devclass argument as a character string expression that corresponds to a valid device class name. See the DVI$_DEVCLASS item in the $GETDVI system service for additional information.

==devtype==

Specifies the device type for which F$DEVICE is to search. Specify the devtype argument as a character string expression that corresponds to a valid type name. See the DVI$_DEVTYPE item in the $GETDVI system service for additional information. NOTE Specifying a device type without specifying a device class will result in an error.

==stream-id==

A positive integer representing the search stream identification number. The search stream identification number is used to maintain separate search contexts when you use the F$DEVICE function more than once and when you supply different search criteria. If you use the F$DEVICE function more than once in a command procedure and if you also use different search criteria, specify stream-id arguments to identify each search separately. If the search criteria are changed in a call before the device name list is exhausted, the context will be reinitialized and the search will restart. If you omit the stream-id argument, the F$DEVICE function assumes an implicit single search stream. That is, the F$DEVICE function starts searching at the beginning each time you specify different search criteria.

=Examples=

$ START:
$ DEVICE_NAME = F$DEVICE("*0:","DISK","RA60")
$ IF DEVICE_NAME .EQS. "" THEN EXIT
$ SHOW SYMBOL DEVICE_NAME
$ GOTO START

This command procedure displays the device names of all the RA60s on a unit numbered 0. Because no stream-id argument is specified, F$DEVICE uses an implicit search stream. Each subsequent use of the F$DEVICE function uses the same search criteria to return the next device name. After the last device name is displayed, the F$DEVICE function returns a null string and the procedure exits.

[[Category:Lexical Functions]]

F$DEVICE() - Revision history

Jane.doe at 05:12, 6 April 2023

Darya.zelenina: Created page with "'''F$DEVICE''' is a lexical function that returns the device names of all devices on a system that meet the specified selection criteria. Note that the d..."