def binary_search(arr, key):
    store_middle = 0
    length = len(arr)
    while store_middle <= length:
        middle = (store_middle   length) // 2
        if arr[middle] == key:  # throws list index out of range
            print(f"Key: {key} is in the {middle} list index")
            break
        else:
            if arr[middle] < key:
                store_middle = middle   1
            else:
                length = middle - 1
    return key


binary_search([2, 3, 5, 8, 14, 12], 14)

The function searches for the 'key' in the given array. When I provide the 'key' larger than 12 the function throws 'list index out of range'. I can't figure out the reason why, it doesn't make any sense why this is happening.

CodePudding user response：

while store_middle <= length

When store_middle = length, you'll cause the error, since the last valid index has value len(arr)-1. Just change it to

while store_middle < length

CodePudding user response：

A couple of things:

• When store_middle and length both equal to len(arr), mid will be out of bounds according to the existing logic.

  To fix this, either set length = len(arr) - 1 or update the loop condition to be while store_middle < length. The former is usually preferred as it can be easily updated to find a "lower bound".

• Binary search works on a sorted container. If you're trying to find something in this array [2, 3, 5, 8, 14, 12], binary search won't work.