Tandy TRS-80 Owner Manual & Programming Manual page 81

.APPENDIX
C
610 NEXT
N
620 CLOSE
#1
630 END
SAMPLE
PROGRAM
#4
SEARCH FOR
A NAME
Since the
file
you
created
in
"Sample Program #3"
is
already in alphabetical order,
you can immediately
find
the
name
you
want. This
program shows
how.
10
'
Search
a
1
ist
20
'
30
'
(NOTEs This program requires
that
a
file called "NAMES/NOS
40
'
exists
—
see
"Create
list and
alphabetize
—
Sample program
#3)
50
'
This program searches
a
disk
file which holds names and
60
'
phone numbers
in
alphabetical
order. The file
is a
direct
70
'
access file called "NAMES/NOS",
is
35
bvtes
long* and
80
'
is
formatted
as follows: 24
bvtes for the name;
3
bvtes
90
'
for the area
code? 8 bvtes
for the phone number.
The
100
'
program uses iterative
searching.
110 '
120
OPEN "D",#l, "NAMES/NOS"
,35
130
FIELD #1,24 AS NAME*,
3
AS
AREA*,
8
AS
PHONE*
140 CLS
150
PRINT
3
99 ,"ENTER NAME(LAST,
FIRST
MI)
160
LINE INPUT NM*
170
'
180
'
Initialization
of
variables
190
*
200 Nl*
=
NM*
210
IF
LEN(NM*>
<
24
THEN 800
220
IF
LEN(NM*)
>
24 THEN 820
230
FIRST
=
1
240 MID -
INT(
(L0F(l)+l)/2)
250 LAST = LOF(l)
260 CNT =
270 '
280
'
Program checks
the last
record first because
it
won't
290
'
be
checked
in
the
regular-
search
300
'
310 GET #1,LAST
320
IF
NAME*
= NM* THEN 450
330
'
340
'
Program keeps comparing NM*
with NAME* from record MID
350
'
until NM*
is
found
or
enough
records have been seen
360
'
to
show that
it
isn't
in
the file
370
'
380 GET #1,MID
390
IF
CNT
>
(L0F(l)+l)/2 THEN 710
400
IF
NAME*
<
NM* THEN 570
410
IF
NAME*
>
NM* THEN 640
420
'
430
'
When NM*
is
found
it
is
printed
out
440
'
450 CLS
460 PRINT
3 104,
NAME*
470 PRINT
a 136,
"
("
?
AREA*
5" )"
;
PHONE*
480 PRINT
3 195, "PRESS <ENTER>
TO CONTINUE,
"
490 PRINT
3
227,
"ELSE PRESS
<Q>
TO QUIT"
500 AN* =
INKEY*
510
IF
AN*
= "Q"
THEN CLOSE: END
520
IF
AN*
= CHR*(13) THEN
140
530 GOTO 500
540
'
550
'
Subprogram
for when NAME*<NM*
560
'
570 FIRST
= MID
580 MID
=
(MID+LAS'D/2
590 CNT =
CNT +
1
600 GOTO 380
6.1.0
'
620
'
Subprogram
for when NAME*>NM*
630
'
640 LAST =
MID
650 MID
=
<MID+FIRST)/2
660 CNT =
CNT
+
1
670 GOTO 380
680
'
690
'
Subprogram
for when NM*
is
not
f o u n
d
700
'
710 CLS
720 PRINT
3 100,
Nl*;" NOT FOUND"
730 PRINT
3 132, "TO TRY AGAIN
PRESS <ENTER>"
740 AN* = INKEY*
750
IF
AN* =
"
"
THEN 740
760 GOTO 140
770
'
780
'
Subprograms
for modifving
NM*
to a
20 bvte string
71