CODEWITHSUNDEEP
pythonpython-2.x
Chrysoula Kaloumenou
Chrysoula Kaloumenou

Reputation: 51

Conditional won't execute properly

I wonder if you could help me with the code below:

min = None
max = None
while True:
    input = raw_input("Please enter number: ")
    if input == "done":
        break
    else:
        try:
            input = float(input)
        except:
            continue



    if max < input:
        max = input
    elif min > input:
        min = input

    print min
    print max

It looks right to me, but the elif statement which gives a value to min always prints None. Could you please explain why?

Upvotes: 0

Views: 54

Answers (2)

keredson
keredson

Reputation: 3088

Your min > input is always going to be false if min is None, hence why it never gets set.

Also you don't want the elif. The first number is both the min and the max.

Fixed:

min = None
max = None
while True:
    input = raw_input("Please enter number: ")
    if input == "done":
        break
    else:
        try:
            input = float(input)
        except:
            continue



    if max is None or max < input:
        max = input
    if min is None or min > input:
        min = input

    print min
    print max

Good luck!

Upvotes: 0

Martijn Pieters
Martijn Pieters

Reputation: 1121306

None > number is never true, because Python 2 sorts None before any other type. Don't compare numbers with None.

Either test for None explicitly, or replace None with an infinity value.

Testing for None:

if max is None or max < input:
    max = input
elif min is None or min > input:
    min = input

Setting the values to positive or negative infinity:

min = float('inf')
max = float('-inf')

By setting min to positive infinity, any other number is guaranteed to be smaller; the same applies to max negative infinity.

Upvotes: 4

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