Binary Search implementation using Python.

binary_search.py

def search(arr, x, lowest_index, highest_index):
    #find the middle index
    middle_index = lowest_index + (highest_index - lowest_index) / 2
    print "Middle index is ", middle_index

    # checks whether the value is in the middle index
    if (arr[middle_index] == x):
        return middle_index
    elif (arr[middle_index] > x):
        # checks in <- direction
        return search(arr, x, lowest_index, highest_index - 1)

    else:
        # checks in -> direction
        return search(arr, x, middle_index + 1, highest_index)

# array to pass as variable
arr = [1, 3, 5, 7, 9, 11, 15, 17, 19]

# result of the search
index = search(arr, 3, 0, len(arr))

#checks whether result is -1 or other integer value
if index != -1:
    print "Element is present at", index
else:
    print "Your searched item is not in the array"