Radio Shack TRS-80 model III Owner's Manual page 148

DISK BASIC
First
we
decide
what
the data
image
is
going
to
be. Let's say
we
want
it
to
look
like this:
english unit
) metric
unit,
factor (ENTER)
For example, the stored data
would
start out:
IN->CMf 2*54001
CENTER)
The
following
program
will create
such a data
file.
Note: X'OD' represents
a carriage return.
10
OPEN
"0"
tl
t"METRIC/TXT"
20
FOR
11=1 TO
7
30
READ UNIT*, FACTR
40 PRINTttl
f
UNIT$;
"
#"
3
FACTR
50
NEXT
G0
CLOSE
70
DATA
IN->CMf 2*54001
t
MI->KM» 1*60935*
ACRE->SQ
*
KM
t
404G.8S E-G
80
DATA
CU.IN->LTR> l*G3871GE-2t
GAL->LTR
,
3*785
30
DATA
LIQ*QT->LTR* 0*84G3»
L6->KG> 0*45359
Line 10 creates a disk
file
named metric/txt, and assigns buffer
1
for sequential
output to that
file.
The
extension /txt
is
used because sequential
output
always
stores the
data as
Ascii-coded
text.
Note:
If
metric/txt already exists, line
10 will
cause
all its
data
to
be
lost.
Here's
why:
Whenever
a
file is
opened
for sequential output, the end-of-file
(eof)
is
set to
the
beginning of
the
file.
In effect,
trsdos
"forgets" that
anything has ever
been written
beyond
this point.
To avoid
this,
you could use e
instead of
o
in line 10.
Line
40
prints
the current contents
of units and
factr
to
the
file.
Since the
spring items
do
not contain delimiters,
it
is
not necessary to print explicit
quotes
around them.
The
explicit
comma
is
sufficient.
Line 60
closes the
file.
The eof
is
at
the
end of
the last
data item,
i.e.,
0.45359,
so that
later,
during
input,
basic
will
know when
it
has read
all
the data.
Sequential Input:
An
Example
The
following
program
reads
the data
from metric/txt
into
two "parallel"
arrays,
then asks
you
to
enter a
conversion problem.
5
CLEAR 500
10
DIM UNIT*(9)t
FACTRO) 'allows for up
to 10
data pairs
20 0PEN
H
r' tl
"METRIC/TXT"
25
n, =
30
IF
EOF(l) THEN
70
40 INPUT*!
»
UNIT$(II) tFACTR(IX)
147