10 REM Substring
20 BAS$="abcdefghijklmnopqrstuvwxyz"
30 N=12:M=5
40 REM Starting from N characters in
50 REM and of M length
60 SB$=MID$(BAS$,N,M)
70 PRINT SB$
80 REM Starting from N characters in,
90 REM up to the end of the string
100 SB$=MID$(BAS$,N,LEN(BAS$)-N+1)
110 PRINT SB$
120 REM Whole string minus last character
130 SB$=LEFT$(BAS$,LEN(BAS$)-1)
140 PRINT SB$
150 REM Starting from a known character
160 REM within the string and of M length
170 A$=BAS$:B$="b":GOSUB 270
180 SB$=MID$(BAS$,C,M)
190 PRINT SB$
200 REM Starting from a known substring
210 REM within the string and of M length
220 A$=BAS$:B$="pq":GOSUB 270
230 SB$=MID$(BAS$,C,M)
240 PRINT SB$
250 END
260 REM ** INSTR subroutine
270 LB=LEN(B$):C=0
280 FOR I=1 TO LEN(A$)-LB+1
290 IF MID$(A$,I,LB)=B$ THEN C=I:RETURN
300 NEXT I
310 RETURN