Apple IIe - Page 220

220
Apple
lie
Users
Handbook
correspond
to
the
absolute
file
position. This
only
occurs
when
the
file
pointer
is
positioned at
the
beginning
of
the
file.
POSITION
like
all DOS
commands
will
cancel
a READ
or
WRITE
command
. For this reason, execute
POSITION
prior
to
the
ex
ecution
of READ
or
WRITE.
POSITION
f
unctions
by
examining
the
file
byte
by
byte.
When
POSITION
encounters
the
ASCII
code
for
return
,
it
assumes that
the
current
fi
eld
's
ending
point
has
been reached.
If
POSITION
enc
oun
ters an unused byte,
it
will
assume that
the
field requested
doe
s
not
exist. The
following
error
message
will
be
displayed:
END
OF
DATA
The
following
program
illustrates
the
use
of
POSITION:
100
0$
=
CHR$
(4)
110
A$=
"JOHN" :
8$ = " BILL":
C$
= " JACK"
120
PRINT D$;
"
OPEN
TESTS
"
130
PRINT D$;
" WRITE
TESTS
"
140
PRINT
A$:
PRINT 8$:
PRINT
C$
150
PRINT
0$
;
"
CLOSE
TESTS
"
160
PRINT D$;
" OPEN
TESTS
"
170
PRINT D$; " POSITION
TESTS
,
R2
"
180
PRINT D$;
" READ
TESTS
"
190
INPUT
Z$
200
PRINTZ$
210
PRINT
D$;
"
CLOSE
TESTS
"
220
END
)RUN [Ret)
JACK