Function returns true if the specified word is contained within the given string.

                                    ` This code was downloaded from The Game Creators
                                    ` It is reproduced here with full permission
                                    ` http://www.thegamecreators.com
                                    
                                    string$ = "The dog jumped over the cat"

repeat
   cls

   set cursor 0,0
   print instr$(string$, "dog")

until spacekey()



REM Returns true if the specified substring
REM is contained within the given string.

function instr$(string$, sub$)
   L1 = len(string$)
   L2 = len(sub$)
   for x = 0 to L1-L2
      if sub$ = subString(string$,x, x+L2) then exitfunction 1
   next x
endfunction 0


REM Returns a chunk of a whole string
REM starp - is the starting position of the substring that
REM         you want to be returned. The character at that
REM         position is not included in the returned result.
REM endp - is the position of the last character in the string
REM        you want to be returned.
function subString(s$ as string, startp as integer, endp as integer)
   l = len(s$)
   s$ = right$(s$,l-startp)
   s$ = left$(s$, endp-startp)
endfunction s$