100 cls
110 t$ = ""
120 isempty(t$)
130 u$ = "not empty"
140 isempty(u$)
150 end
160 sub isempty(s$)
170   if len(s$) = 0 then
180     print "String is empty"
190   else
200     print "String is not empty"
210   endif
220   if s$ = "" then print "yes, the string is empty"
230   if s$ <> "" then print "no, the string is not empty"
240 end sub