' trim any characters in c$ from the start and end of s$
FUNCTION Trim$(s$, c$)
 Trim$ = RTrim$(LTrim$(s$, c$), c$)
END FUNCTION
 ' trim any characters in c$ from the end of s$
FUNCTION RTrim$(s$, c$)
 RTrim$ = s$
 DO WHILE INSTR(c$, RIGHT$(RTrim$, 1))
   RTrim$ = MID$(RTrim$, 1, LEN(RTrim$) - 1)
 LOOP
END FUNCTION
 ' trim any characters in c$ from the start of s$
FUNCTION LTrim$(s$, c$)
 LTrim$ = s$
 DO WHILE INSTR(c$, LEFT$(LTrim$, 1))
   LTrim$ = MID$(LTrim$, 2)
 LOOP
END FUNCTION