UnderwareDESIGN

[pbcode]

; *=-------------------------------------------------------------------------=*
;
;   This example shows how you could perform a simple linear upon an integer
;  array.  
;
;   What is it ?
;  ================
;
;   Conceptually, a Linear search is the simplest form of searching possible:  
;  It involves simply running all the way  through (sequentially) our data
;  structure (an array in this case) and comparing the each value or string
;  to our search value.  If a match a found we exit and return this elements
;  position.  But if no match was found we return a -1.  

;  Note: While Thankfully in PlayBasic we can we can use the FindArrayCell()
;       function to do the grunt work for us.  Linear searching is a brute
;       force operation. While it'll fast on small sets of data, it can be
;       a real mouth full on larger sets, in particular if you need to perform
;       many searches.    
;
; *=-------------------------------------------------------------------------=*


Size=20

; Fill an array with values from 0 to size
Dim RandomValues(size)
For lp=0 to size
 RandomValues(lp)=lp
next

; Now Shuffle these values so there in a random order
For lp=0 to size
     Item1   =rnd(size)
     Item2   =rnd(size)
 a=RandomValues(item1)
 b=RandomValues(item2)
 RandomValues(item1)=b
 RandomValues(item2)=a
next


; Show the Array contents
Print "RandomValues() Array Contents:"
print ""
For lp=0 to size
 print digits$(lp,2)+" "+str$(Randomvalues(lp))
next



  setcursor 0,0
  cursormargin 300
   Print "Results of Linear searching the RandomValues() array"
   print ""
 
   for lp=0 to 10
 FindValue=rnd(20)
 Print " Searching For Value:"+str$(FindValue)
 Foundat=SearchArray(RandomValues(),FindValue)  
 if FoundAt=-1
    print "Value not found"
 else
    print "Found at array index:"+Str$(foundat)
 endif
 print ""
   next

Sync
waitkey



; =-----------------------------------------------------------------=*
;        Search an Integer Array looking for an Integer Value
; =-----------------------------------------------------------------=*

Function SearchArray(array(),FindThisValue)
   ; Get the current size of this array
 Size=GetArrayElements(Array(),1)
   ; Call Find array cell to locate this element.
 FoundAt=findarraycell(array(), 0,1,size,FindthisValue)
EndFunction FoundAt


[/pbcode]