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Reality V15.0 ()

F-READ command (Proc) (m618403+fread.htm)

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F-READ

Reads an item from a file into a file buffer.

Syntax

F-READ fileBufferNumber itemId altCmd

F-R fileBufferNumber itemId altCmd

Syntax Elements

fileBufferNumber
The number of the file buffer to which the file was assigned that contains the item you want to read. Valid numbers are 1 to 47, but note that 19 and 20 are reserved for system Procs.

fileBufferNumber can be a direct or indirect file buffer reference.

itemId The name of the item to be read. itemId can be a literal string (not enclosed in quotes), or it can be a direct or indirect reference to a buffer or select register containing the item-id that you want to read.

altCmd The command(s) to be executed if the named item cannot be read. Must be on the line immediately after the command itself.

Operation

The F-READ command is always followed by a command line that is executed if the read fails.

If the file to be read has not been opened previously with an F-OPEN command, execution of the Proc terminates with an error message.

If the specified item is not on file, the statement on the line immediately following the F-READ command is executed.

If the read is successful, the statement on the line immediately following the F-READ command is skipped and execution continues with the next line.

Comments

If you are only processing one item from a file, the FB command is preferable to an F-OPEN, F-READ command sequence.

Examples

001 PQN

002 F-READ 1 123-AB

003 XItem 123-AB cannot be found

004 OItem 123-AB found

Reads the item 123-AB into file buffer 1. If item 123-AB cannot be found, the statement on line 3 is executed and the Proc is exited. Otherwise, the message on line 4 is displayed and execution of the Proc continues.

001 PQN
002 OEnter part number+
003 10 IP %3
004 F-READ 7 %3
005 GOTO 25
006 T C,(10,10),"Quantity on hand = ",&7.2
.
.
.
015 25 "Part no. ",%3," not found...Try again",+
016 GOTO 10

Reads the part number (represented by %3) entered at the terminal into file buffer 7. If the part number is invalid, control transfers to label 25 on line 015, and you are given another chance to enter a valid part number. Otherwise, execution continues on line 006.