Non-Recursive Binary Search

int BinarySearch(int[] x, int key)

{
        int low = 0;
        int high = x.length-1;
        int middle = (low+high)/2;
        while ((low <= high) && ( x[middle] != key )) {
           if (key <x[middle]) high = middle-1;
           else low = middle + 1;
           middle = (low + high)/2;
         }
        if (low>high) return -1;
        else return middle;
}


Recursive Binary Search

int BinarySearch(int[] x, int low, int high, int key)

{
    if (low>high) return -1;
    else {
       int middle = (low+high)/2;
       if (x[middle] == key) return middle;
       if (key < x[middle]) return BinarySearch(x,low,middle-1,key);
       else return BinarySearch(x,middle+1,high,key);
     }
}

Initially: int found = BinarySearch(x,0,x.length-1,key);