The Program is:

!find position of B for various n for pos and posr functions

!Note error in text page 125, for posr(Target$,pattern$,position) he

!states that position "equal to 1 means the last character in Target$,

!so position increases in value as you move to the left". Actually,

!position is always measured from the left, as shown below.

LET n=0

PRINT "In string ABCDEABCDEABCDE"

DO until n >= 15

LET n=n+1

LET position = posr("ABCDEABCDEABCDE","B",n)

SET COLOR "red"

PRINT "for n= ";n;" in posr(,,n) the position of B is...";position

LOOP

LET n=0

DO until n >= 15

LET n=n+1

LET position = pos("ABCDEABCDEABCDE","B",n)

SET COLOR "blue"

PRINT "for n= ";n;" pos(,,n) the position of B is...";position

LOOP

END

The output is:

In string ABCDEABCDEABCDE

for n= 1 in posr(,,n) the position of B is... 0

for n= 2 in posr(,,n) the position of B is... 2

for n= 3 in posr(,,n) the position of B is... 2

for n= 4 in posr(,,n) the position of B is... 2

for n= 5 in posr(,,n) the position of B is... 2

for n= 6 in posr(,,n) the position of B is... 2

for n= 7 in posr(,,n) the position of B is... 7

for n= 8 in posr(,,n) the position of B is... 7

for n= 9 in posr(,,n) the position of B is... 7

for n= 10 in posr(,,n) the position of B is... 7

for n= 11 in posr(,,n) the position of B is... 7

for n= 12 in posr(,,n) the position of B is... 12

for n= 13 in posr(,,n) the position of B is... 12

for n= 14 in posr(,,n) the position of B is... 12

for n= 15 in posr(,,n) the position of B is... 12

for n= 1 pos(,,n) the position of B is... 2

for n= 2 pos(,,n) the position of B is... 2

for n= 3 pos(,,n) the position of B is... 7

for n= 4 pos(,,n) the position of B is... 7

for n= 5 pos(,,n) the position of B is... 7

for n= 6 pos(,,n) the position of B is... 7

for n= 7 pos(,,n) the position of B is... 7

for n= 8 pos(,,n) the position of B is... 12

for n= 9 pos(,,n) the position of B is... 12

for n= 10 pos(,,n) the position of B is... 12

for n= 11 pos(,,n) the position of B is... 12

for n= 12 pos(,,n) the position of B is... 12

for n= 13 pos(,,n) the position of B is... 0

for n= 14 pos(,,n) the position of B is... 0

for n= 15 pos(,,n) the position of B is... 0