Search for a string in an array using the binary search.

This example loads a set of strings into an array, then uses a binary search to find the index of a particular string. Please note that the binary search requires the array to be sorted in ascending order.

                                    ` This code was downloaded from The Game Creators
                                    ` It is reproduced here with full permission
                                    ` http://www.thegamecreators.com
                                    
                                    `---------------------------------------------------------
` PLEASE NOTE: The binary search relies on the array being
` sorted in ascending order.
`---------------------------------------------------------
dim GeneralArray(0) as string

`-------------------------------------
` Read the inline data into our array.
`-------------------------------------
restore __inline_data

repeat
   read temp$

   if temp$ <> ""
      array insert at bottom GeneralArray()
      Index = array count(GeneralArray()) - 1

      GeneralArray(Index) = temp$
   endif
until temp$ = ""

`----------------------------
` Show the data in the array.
`----------------------------
print "Here is the data in the array."
for index = 0 to (array count(GeneralArray()) - 1)
   print "INDEX " + str$(index) + ": " + GeneralArray(index)
next index

Name$ = "Roger DBCoder"
Index = BinaryStringSearch(array count(GeneralArray()), Name$)

if Index <> -1
   print : print "The index of the string '" + Name$ + "' is " + str$(Index)
else
   print : print "The index of the string '" + Name$ + "' could not be found."
endif

suspend for key
end

function BinaryStringSearch(Bottom, SearchString$)

   top = 0
   middle = 0
   found = 0
   returnvalue = -1

   while (found <> 1) and (Bottom >= top)
      middle = ((top + Bottom) / 2)
      if (middle = 0) and (Bottom = 1) then middle = 1

      if (SearchString$ = GeneralArray(middle))
         found = 1
      else
         if (asc(left$(GeneralArray(middle), 1))) < (asc(left$(SearchString$, 1)))
            top = middle + 1
         else
            Bottom = middle - 1
         endif
      endif
   endwhile

   if found = 1
      returnvalue = middle
   else
      returnvalue = -1
   endif

endfunction returnvalue

__inline_data:
data "Adam Presley", "Agent Smith", "Data DooDoo", "John Smith", "Roger DBCoder"