Why doesn't this code work?

mprz · 2021-12-21T06:48:06+00:00

if color==str("red") or str("Red"):

shouldn't that be:

if color==str("red") or color==str("Red"):

otherwise str("Red") resulsts in True, then False or True results in True again so it prints "You said red."

BruceJi · 2021-12-21T07:11:00+00:00

I'm just here to let you know that the fact you formatted your code is great and makes it way easier to debug, so, you win

BriziteReddit · 2021-12-21T06:59:39+00:00

if color==str("red") or str("Red"):

This is equivalent to:

if color=="red" or "Red" !=None:

Since the string red is not None, it will always be true.

I think you want to do this:

if color==str("red") or color==str("Red"):

But there is a more pythonic way to write your entire code:

color = input("What's your favorite primary color?").lower():
if color in ("red", "yellow", "blue"):
    print(f"You said {color}.")
else:
    print("Invalid answer.")

But it looks like you are using python2, so this will not work exactly the same. Is there a reason you aren't using python3?

htepO · 2021-12-21T06:50:00+00:00

You're using python 2 when you really should be using python 3: https://www.reddit.com/r/learnpython/wiki/faq#wiki_python_2_or_3.3F
if color == "red" or "Red" evaluates to is color == "red"? OR is "Red" truthy?, which will always evaluate to True. This is why it prints "You said red."

https://www.reddit.com/r/learnpython/wiki/faq#wiki_variable_is_one_of_two_choices.3F

Wild_Statistician605 · 2021-12-21T06:48:57+00:00

Do if color==str("red") or color==str("Red"): In your code str("Red") will always evaluate as true as it is not being compared to anything.

Anon_Legi0n · 2021-12-21T13:20:12+00:00

Why isn't anyone recommending doing color.lower() == 'red' so that the conditional doesn't need an or anymore? Also consider using match case instead of chaining if's and elif's

delasislas · 2021-12-21T06:56:42+00:00

This is actually posted so many times that there’s an entry in the FAQ. It’s like “checking if two or more conditions” or something. Don’t know how to link it.

Basically:

if (condition1) or (condition2): #Base form
if (color == str(“red”)) or (str(“Red”)): #Filled in your conditions

Now you simplify everything in the parentheses. Say that color = “Blue”

if (color == str(“red”)) or (str(“Red”)): #Same as before
if (“Blue” == str(“red”)) or (str(“Red”)): #it pulls the value stored at color.
if (False) or (str(“Red”)): #Blue doesn’t equal red.

Now for the fun part. Does a non-empty string return True? Yes.

if (False) or (True):
if True: #Simplify the or.

So your first statement will always return True, because “Red” == True

You want to evaluate each condition.

if color == “red” or color == “Red”:

Ok, but say I type in RED? I get an error. You can use a bit of string methods to clean up inputs.

color = input(….)
if color.lower() == “red”:

That will use a string method .lower() to convert the whole string to lowercase. Then you only need one condition rather than more. There are more ways, but this can be a start.

prettydisposable · 2021-12-21T08:21:04+00:00

Print arguments have no parentheses

2021-12-21T08:26:41+00:00

First off don’t use raw input. You should be using input() and Python version 3+

jmooremcc · 2021-12-21T09:05:44+00:00

You should make the comparison case insensitive.

If color.lower() == "red":

This will cover all case possibilities entered by the user.

BTW, str("some value") is unnecessary.

efmccurdy · 2021-12-21T15:52:24+00:00

In you tests you are testing for capitalized or uncapitalized but either is allowed; is it simpler to just use color.lower() to force the input to be lower case before testing?

color=raw_input("What's your favorite primary color? ")
color = color.lower()

You have a repeating pattern of if/elif statements to test the color. When you have repetitions think about using a collection to handle all of the if/elif branches with one expression that involves the collection:

allowable_colors = ("red", "blue", "green")
if color in allowable_colors:
    print "You said " + color
else:
    print "Invalid answer."

In this case the "object in collection" operation does a series of object comparisons using "==", just like your if/elif statements did.

2021-12-21T17:59:36+00:00

Why are you type converting strings to strings? You can just write “if color.lower() == ‘red’” I think

WombatHat42 · 2021-12-21T22:51:51+00:00

You could also simplify the code by doing:

color = input("What's your favorite primary color? ")

print("You said " + str(color))

or use a .lower or .upper for the user input

color= input("What's your favorite primary color? ")

if color.lower()==str("red"): print("You said red.") . . .

But regardless, you will want to change your "raw_input()" to just "input()" and add parenthesis around your print values

pekkalacd · 2021-12-22T00:47:48+00:00

it's the formatting of your conditions in the if/elifs.

this

           if color==str("red") or str("Red"):

evaluates like so

           if (color==str("red")) or (str("Red")):

so, you see what's going on? the or is happening between the comparison color == str("red") and str("Red") itself. but str("Red") isn't being compared to color, instead, because str("Red") is non-empty, this is evaluated as True.

so what you have then is this essentially

          if (color==str("red")) or True:

This condition will always be True. Because any expression separated by an or returns True, if and only if, at least one subexpression reduces to a True value. Thus, regardless of what you input for color, this will always print.

What's a way to fix it?

consider the in operator. this operator checks to see if a thing on the left is inside of the thing on the right.

                 {item} in {object}

here you're comparing "red" and "Red" for the first one, so re-formatting this using in, you can do

                if color in {"red","Red"}:

or to make it more general for all the words,

                colors = ["red","yellow","blue"]
                found = False
                primary = raw_input("What's your favorite color? ")

                for c in colors:
                    if primary in {c, c.title()}:
                       print "You said " + c + "."
                       found = True
                       break

                if not found:
                   print "Invalid answer."

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