ONE
THING
AT A TIME
By adding
line
105
to
the
program, the Computer
checks to
see
if
you've reached
the End before
inputting
the next check.
If
you
have,
line 130 clo-
ses
communication
to
the
file.
DETAILS...
So far, "CHECKS/DAT" has been
easy to
handle,
but not very useful. You would probably like
to
add
more
details:
CHECKS
PAYABLE TO AMOUNT
EXPENSE
DR. HORN
45.78 MEDICAL
SAFEWAY
22.50 FOOD
FIRST CHRISTIAN
20.00
CONTRIB.
OFFICE SUPPLY 13.67
BUSINESS
Change lines 25 and
115,
and
add some lines by
typing:
25 WRITE
ttl
t ^5.
78
27 WRITE #1
t
"MEDICAL"
110 INPUT #1
t ft$i
B»
Ct
115 PRINT At t
B
>
Ct
LIST the program.
This
is the way it should
look
now:
#1
> "CHECKS/DAT"
"DR. HORN"
#1
. "CHECKS/DAT
1
=
-1
THEN 130
10 OPEN
"0"
t
20 WRITE
*1
>
25 WRITE «1 , a5.
78
27
WRITE «1
t "MEDICAL"
30 CLOSE
«1
100
OPEN
"I"
»
105 IF E0F(1)
110 INPUT #1
, A$i Bt C$
115 PRINT A$ >
Bi
Ct
120 GOTO
105
130 CLOSE
*1
Now RUN
it.
A GOOD TIGHT PROGRAM
What if
you
need
to store a whole list
of checks?
Continue
to plod along
with this program,
and
it'll
soon be
unbearable.
Here, we have
a
tight
program which asks you to
INPUT all
your
data, stores it on disk, and reads
it
back into memory.
Erase memory and type:
5 CLS
10 OPEN
"O"
*
*1
i "CHECKS/DAT"
20 INPUT "CHECK PAYABLE TO
:"i
A$
30
IF At
=
""
THEN 80
40 INPUT
"AMOUNT :
*"!
B
50 INPUT
"EXPENSE
:" i C$
GO WRITE «li
At
t
B t C$
70 GOTO 20
80 CLOSE *1
80 CLS
100 PRINT
"YOUR
CHECKS ARE STORED ON DISK"
110 INPUT "PRESS
<ENTER> TO READ THEM"! At
120 OPEN "I"
t
alt
"CHECKS/DAT"
130 IF E0F( 1
)
=
-1
THEN
170
140 INPUT *li At i
Bt Ct
150 PRINT a$; b; Ct
1G0 GOTO 130
170
CLOSE
»1
RUN it. Input any
checks. When
you want to quit,
simply
press (ENTER) in
answer
to
the
check
pay-
able to
:
prompt. For
example:
(ENTER)
CHECK PAYABLE
TO :? GOODY BANK
(INTER)
AMOUNT :$?
230.97
EXPENSE
CHECK
CAR
(ENTER)
PAYABLE TO
:?
(ENTER)
YOUR
CHECKS
ARE STORED ON
DISK
PRESS
(ENTER)
TO READ THEM?
(ENTER)
GOODY
BANK
230.87 CAR
PROGRAMMING
EXERCISE
#5.1
Write a program which
will
print
only
those
checks which were for
JAR
expenses.
The
answers to all the
"Programming
Exercises"
are in
Appendix A.
CHAPTER
CHECKPOINT
1. What is a buffer
#1?
2. Why must you OPEN
a
disk
Hie?
3.
Why must you CLOSE
it?
4.
What is
the difference
between
a file OPEN
for input
and
output?
28
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