Commodore PET User Manual page 220

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If A$<B$. switch strings
Clear screen
Input numeric strings
Subtraction loop (based on
lines 1020-1100 of the addition
program)
} Clear strings and variables
THEt.j L=L+1 }
Truncate leading zeros
THEN
1
::::LEN
C
C$)
and blanks
1 (1
FR
l
tH" :'>f.:+;:+;:;:;UI:Tf':ACT
l OtJo+::+::+;" :
Pi":
l
tH
,:2(1
HJPUT A$., I:$
30 BLAtjf<$=" "
1
4(1 :'·';=LENCA$)· 'T'=LEN(E:$)
Right justify strings (from
50 IF ;' · ' ; ' C T' THEN A$=LEFT$ CE:LAt·JK$ ..
'/--i·':)
+A$
lines 20-60 of the addition
60 IF 'T'<>'; THEN B$=LEFT$(E:LANK$ . .
>~-'T')+E:$
program)
1::'5 IF ' · ...AL CA$) =',...AL CE:$) THEN C$=" (1" : GOTO 115(1
70 IF VALCA$»=VALCB$) GOTO 1000
80
X$=A$A$=B$B$=X$
90 S=l
1000 REM*:+;SUBTRACTION ROUTINE.:+:
1010 FOR I=LENCA$) TO 1 STEP-l
1020 A=VALCMID$CA$,I,l»
:1. O:~:O
A=A+D: D=O
1040 B=VALCMID$CB$, 1,1»
105(1 IF CA-B)<0 THEN D=-l A=A+I0
1(160 C=A-E:
1070 C$=RIGHT$C8TR$CC),1)+C$
10::;:(1 t·J[;:-';T 1
1090 FOR 1=1 TO LENCC$)
1100 IF VALCMID$CC$,I,l»=O
1110 IF VALCLEFT$CC$,I»<>0
1120
t·JEi·~T
1
1130 C$=RIGHT$CC$,LENCC$)-L)
1140 IF 8=1 THEt·j C$="-"+C$
Il
:;(1
PI": 1
HT : FR
1
tH"
A~JS~·JER="
. ; C$ : PR
1
NT
116(1
[:$=1111. A$=IIII . 1::$=1111: ;:'::$:::1111
1165 A=0B=0 C=0D=OS=0:X=0:Y=0
11721 CiOT020
118(1
am
***SUBTRACTIOH***
?123456789012
??57943572
AN8WER= 123398845440
207