Commodore PET User Manual page 226

Step 5: Concatenate the answer strings. CH$ and CL$, together by
numeric string concatenation. They are concatenated in statement 1120:
1121::1 C$=CH$+CL$
C$=CH$c::J+ CL$c:=::J
C$=
1 1
Only the rightmost "F" numbers from CL$ are concatenated to CH$ to avoid
concatenating any leading blanks in CL$ (see the earlier "Numeric Strings" sec-
tion for further discussion).
Step 6: Truncate leading zeros in C$ before C$ is printed. Leading zeros
are subtracted in the same way for Multiple Integer Subtraction as for Numeric
String Subtraction (see step 5, "Numeric String Subtraction:' page 205). Lines
1130 through 1170 truncate leading zeros just prior to printing C$:
1130 FOR 1=1 Ta LENCC$)
1140 IF VALCMID$CC$,I,I»=0 THEN L=L+1
1150 IF VALCLEFT$CC$,I»<)0 THEN I=LENCC$)
1160 t'~E~-:;T 1
1170 C$=RIGHT$CC$,LENCC$)-L)
. 1 1::::1::1 IF S=1 THEt~ C$="-"+C$
If A$ and B$ had been switched, S would have been set to 1, signaling a negative
answer, and thus a negative sign would be concatenated to the front of C$ at
1180.
Step 7: Print the answer and clear out variable strings before allowing
another problem to be input.
J.
190
PF:
1NT •
F'F:
1tH" At·jS~,jER= ".; C$ •
F'R
1tH
.1200 A$="'" E:$="" C$="'" CH$="" •CL$=""
1205 AH=0·AL=0·BH=0BL=0 F=0.S=0X=0.Y=0
121(1 GOTO 2t1
.1220
am
213