1. Binary Search :

Step 1 :Set BEG := LB , END := UB and MID := INT((BEG+END)/2)
Step 2 : Repeat steps 3 and 4 while BEG <=END and DATA [MID] != ITEM.
Step 3 : If ITEM < DATA[MID] then:
    Set END = MID-1.
   Else:
   Set BEG := MID + 1.
Step 4 : Set MID = INT((BEG + END)/2).
Step 5 : If DATA[MID] := ITEM, then :
    Set LOC := MID
   Else :
Set LOC := NULL
Step 6 : Exit.