If/else statement executing incorrectly

Question

Learning python and currently learning the bisection method of solving problem. I'm writing code that should take in a users guess from 0 to 100 and attempt to find that guess using bisection. Here's the code:

answer = raw_input('Please think of a number between 0 and 100')
#I've been using 80 as my test case 

low = 0
high = 100

guess = (low+high)/2

while guess != answer:

    if guess < answer:
        low = guess
    else:
        high = guess


    guess = (low+high)/2

What I've realized is that when my guess < answer is false the else block doesn't execute, so my high number never changes. Why is this happening? Am I overlooking something here?

Answer 1

You need to convert user input to integer (raw_input() returns a string):

answer = int(raw_input(...))

Comparison fails because you are later comparing an integer to a string (which works in Python2, but would not work in Python3):

>>> 10 < "50"
True
>>> 75 < "50"
True