Commodore PET User Manual page 204

The following statements right-justify the shorter of the numeric strings A$
and B$ and fill it with leading zeros until it equals the length of the longer string. X
is assigned ta the length of A$. and Y ta the length of B$:
313 BLFtt-lI<$="
413 X=LEt-l(Ft$):Y=LEt-l(B$)
513 IF X<Y THEt-l Ft$=LEFT$(BLFtt-lK$,Y-X)+Ft$
613 IF Y<X THEt-l B$=LEFT$(BLFtt-lK$.X-Y)+B$
BLANK$ in line 30 is a buffer string ta fill the shorter numeric string with blanks.
Lines 50 and 60 use the LEN function ta compare X (the length of A$) ta Y (the
length of B$l. and subtract the length of the smaller string from the length of the
larger string. In our example B$ is shorter than A$, sa the length of B$ is
subtracted from the length of A$.
613 IF Y<X THEt-l B$=LEFT$(BLFtt-lK$.X-Y)+B$
-...-
Length of smaller string subtracted
from length of larger string
If the length of A$ is 16 digits and the length of B$ is 8 digits, the difference
is 8 digits:
A$ 111213141516171819101112131415161
x
= 16
1
X-y =81
B$ 15171914131517121 y = 8 16-8 = 8
The number of blanks concatenated onto the front of B$ is the difference of
the two lengths. Since the difference is 8, eight blanks are taken fram BLANK$ ta
fill the shorter string. Blanks are then concatenated ta the front of the shorter
string B$ with the following statement:
LEFT$(BLANK$(X -Y))+B$
The procedure is as follows:
B$=LEFT$(BLANK$,X-Y) +B$
B$=LEFT$(BLANK$.16-8) +B$
B$=LEFT$(BLANK$.S) +B$
B$=LEFT$(j16I16I16I16I16!16I16I16I16I16I16I16I16I16I16I16I.8) +B$
B$-I16I16I16J16I16I16I16I161 +=15=17=\91"-41=31""51=71""' 2 1
B$-I16I16I16I16I16I16I16I1615171914131517121
A$=11121314151617lsJ91 011121314/5/61 B$=I16I16I16/16I16I16I16I1615171914131517/2/
16 digits 16 digits
191