weof Statement

The weof statement writes an eof (end of file) mark to the currently attached magnetic media.

Syntax

weof var [then statement.block {[else|onerr] statement.block}]

Description

The then clause is executed if the operation was successful. If the operation was unsuccessful, the else or onerr clause is executed.

The onerr clause can be used to check for tape error conditions by interrogating the system(0) function. Either else or onerr can be specified, but not both.

See then/else Statement Blocks for an explanation on the use of then and else clauses in statements that allow or require them.

Example(s)

In this subroutine, a series of tape files are written using items in a previously formatted disk file. The items represent tape blocks and the IDs are numbered 1 though M, where M is the block count. When a null item is encountered, the logic assumes that an eof is to be written to tape. Two eof marks indicate an end-of-data condition.

subroutine outtape

execute ’t-att ’:blocksize

* tape not attached

if system(0) = "1" then

err=system(0)

return

end

ctr=1; eot=0 ; err=0

loop

read block from tape.hold.file,ctr then

* a null block in the file

if block=’’ then

* write an eof.

weof else err=system(0)

end else

writet block else err=system(0)

end

end else eot=1

until eot or err do

ctr=ctr+1

repeat

* at end-of-tape

if eot then

* write 2 eof’s

weof then

weof else err=system(0)

end else err=system(0)

end

return