basic.weof
Writes an end-of-file mark to tape.
Syntax
weof variable [then | else | onerr statement.block]
Description
writes an 'end of file' mark to the currently attached magnetic media.
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 may be used to check for tape error conditions by interrogating the 'system(0)' function. Either 'else' or 'onerr' may be specified, but not both.
See the 'then/else construct' for an explanation on the use of 'then' and 'else' clauses in statements that allow or require them.
Example
In this 'subroutine', a series of tapes 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's indicate an end-of-data condition.
subroutine outtape
execute 't-att ':blocksize
if system(0) = '1' then ; * tape not attached
err=system(0)
return
end
ctr=1; eot=0 ; err=0
loop
read block from tape.hold.file,ctr then
if block='' then ;* a null block in the file
;* 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
if eot then ;* at end-of-tape
weof then ; * write 2 eof's
weof else err=system(0)
end else err=system(0)
end
return
See Also
Command Name
Type
Description
statement.block
Definition
one or more statements that follow a Pick/BASIC decision-path related token such as, but not limited to, 'then', 'else', 'locked' and 'onerr'.
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