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The following is my code that calculates <, > incorrectly. About 3X into giving raw_input it will do things like value 12 < 4. I have added several float commands to try to keep it from having problems with string and int. I'm very new to coding. 

largest = None smallest = None while True: num = raw_input("Enter a number: ") if num == "done" : break try: float(num) except ValueError: print "Invalid input" break float(num) if largest is None: largest = num float(largest) if smallest is None: smallest = num float(largest) if num > largest: largest = num float(largest) if num < smallest: smallest = num float(smallest) print num print "Maximum", largest print "Minimum", smallest
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    What does "do things like value 12 < 4" mean? Commented Mar 25, 2016 at 17:46
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    you're not comparing 12 < 4; you're comparing "12" < "4" Commented Mar 25, 2016 at 17:46
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    Also, just saying float(smallest) doesn't change smallest. You need to do smallest = float(smallest). Commented Mar 25, 2016 at 17:47
  • @zondo is correct. In your case, if you just modify the try block to try: num = float(num) then i dont think you will have to make any other changes. Just that you can remove all the float() calls. Commented Mar 25, 2016 at 18:04

4 Answers 4

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float(num) computes the floating-point value of num, but doesn't do anything with it; in particular, it doesn't change the value of num. You'll need an assignment to do that.

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float does not change the variable in-place - it returns a cast value, which you are ignoring by not saving it anywhere. Just assign it, and you should be OK:

try: num = float(num) except ValueError: print "Invalid input" break if largest is None: largest = num if smallest is None: smallest = num if num > largest: largest = num if num < smallest: smallest = num print num
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In your current code, after casting num as a float, you never actually assign it to anything.

float(num)

Instead you will want to re-assign num after the conversion

num = float(num)

If you don't do this (as in your current code), when you're performing the comparisons, you're doing a string comparison rather than a numeric comparison.

"12" < "4" # True
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I think you need to remove that initial conversion to float in order to remove the downvote on your answer, since the user is using the input given to a string "done". Just my wildest guess though!
@Sнаđошƒаӽ Yup! Just realized that. Thanks for pointing that out.
@Cyr1lfiggus If Suever answerd your question, please mark their answer as accepted (green check).
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You don't change the value in num in your code. Typing "float(num)" doesn't really do anything because it's just temporarily casting that variable as a floating point number. To actually change the value I suggest the following edits.

largest = None smallest = None while True: num = raw_input("Enter a number: ") if num == "done" : break try: float(num) except ValueError: print "Invalid input" break num = float(num) if largest is None: largest = num if smallest is None: smallest = num if num > largest: largest = num if num < smallest: smallest = num print num print "Maximum", largest print "Minimum", smallest
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Thank you very much for the quick feedback!!

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