🔒 Else statement that keeps on printing!

[cyan onyx]

Currently on week 1 of CS50P. I have an else statement that keeps on printing even though the scenario is true, and wondering what I could implement to avoid this problem. I know that I didn't add a proper conditional to it, it has repetitive code, such as if and endswitch as well.

extensions_files = input("File name: ")

extensions_files = extensions_files.replace(" ", "")

if extensions_files.endswith(".jpg"):
print("image/jpg")

if extensions_files.endswith(".jpeg"):
print("image/jpeg")

if extensions_files.endswith(".pdf") or ("PDF"):
print("application/pdf")

if extensions_files.endswith(".png"):
print("image/png")

if extensions_files.endswith(".gif"):
print("image/gif")

if extensions_files.endswith(".txt"):
print("text/plain")

elif extensions_files.endswith(".zip"):
print("application/zip")

else:
print("application/octet-stream")

[royal flare]

@cyan onyx

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[raven narwhal]

!or This is a common logical error. Check this out 👇

[royal flare]

The or-gotcha

When checking if something is equal to one thing or another, you might think that this is possible:

# Incorrect...
if favorite_fruit == 'grapefruit' or 'lemon':
    print("That's a weird favorite fruit to have.")

While this makes sense in English, it may not behave the way you would expect. In Python, you should have complete instructions on both sides of the logical operator.

So, if you want to check if something is equal to one thing or another, there are two common ways:

# Like this...
if favorite_fruit == 'grapefruit' or favorite_fruit == 'lemon':
    print("That's a weird favorite fruit to have.")

# ...or like this.
if favorite_fruit in ('grapefruit', 'lemon'):
    print("That's a weird favorite fruit to have.")

[cyan onyx]

Oh, I completely forgot about that! Thank you, I also never knew about the reverse word. Thanks.

Looks better? if extensions_files.endswith(".png") or extensions_files.endswith("PDF"):
print("image/png")

[vast acorn]

pdf isn't image

str.endswith actually allows you to provide multiple options

if extensions_files.endswith(('.pdf', '.PDF'))

you could also do:

if extensions_files.lower().endswith('.pdf')

[clear dawn]

Main problem with your code is actually that those ifs are all separate.
Until last if-elif-else - those three are grouped. But only those
So the else will always print unless that if or that elif is True. Any other if? This group doesn't care about them

!e

a = 1
if a==1:
    print("one")
if a==2:
    print("two")
else: # <-this is connected only to the previous if
    print("many")

[royal flare]

:white_check_mark: Your 3.13 eval job has completed with return code 0.

001 | one
002 | many

[cyan onyx]

Shouldn't it be: if extensions_files.lower().endswith('.PDF')?

[clear dawn]

Why lowercase string would have uppercase PDF?

[vast acorn]

no, because if you're making it lowercase, you want to check for 'pdf' which is also lower

[cyan onyx]

Oh, I see

How about checking if it is capitalized?

[vast acorn]

.upper()

if you want to check if something is capitalized, it's .isupper()

[cyan onyx]

Thanks!

I'll make these changes, thank you guys! Is there anything I could do to reduce this code?

[vast acorn]

Yes, but unless you've learned about dictionaries already, I wouldn't worry about it just yet

[cyan onyx]

No, I haven't. Thank you once again.

[cyan onyx]

I was thinking if it is capitalized (PDF), then it should also find the lower string of it?

[cyan onyx]

Since I don't want all three to just be connected. I want all the if statements to one else statement. Should I simply just add an elif statement and a better conditional, for instance, elif not in extensions_files.endswith(".zip", ".txt", ...). I haven't used a not in conditional before, so I don't know if this would work?

[vast acorn]

we apply .lower() so we don't have to check both cases

[vast acorn]

you want elif here. We can only have 1 extension. If we determine it is .txt, then we don't need to keep checking if it's also png, pdf, etc

[cyan onyx]

Oh I understand, I need to add the upper and lower in order to get it correct

[vast acorn]

you don't need both, just pick 1 case to check

if you do .upper(), then check for "PDF". If you do .lower(), then check for "pdf"

it doesn't really matter which one you pick, just make sure you're consistent

[cyan onyx]

Okay

[cyan onyx]

extensions_files = input("File name: ")

extensions_files = extensions_files.replace(" ", "")

if extensions_files.endswith(".jpg") or extensions_files.endswith(".jpeg"):
print("image/jpeg", end="")

elif extensions_files.lower().endswith('.pdf'):
print("application/pdf")

elif extensions_files.endswith(".png"):
print("image/png")

elif extensions_files.endswith(".gif"):
print("image/gif")

elif extensions_files.endswith(".txt"):
print("text/plain")

elif extensions_files.endswith(".zip"):
print("application/zip")

else:
print("application/octet-stream")

[royal flare]

Hey @cyan onyx!

Please edit your message to use a code block

```py
print('Hello, world!')
```

This will result in the following:

print('Hello, world!')```

[vast acorn]

remember you can use multiple options in a single endswith. It will be handy for jpeg

if extensions_files.endswith(('.jpg', '.jpeg'))

[cyan onyx]

Oh, great!. I will add that since it is shorter. Thank you guys for your help. This might be off topic, but I'm wondering how you understand Python so well?

[vast acorn]

time, practice, experience

you're 1 week in

I'm 7 years in

[cyan onyx]

That's impressive. Thanks once again.

[vast acorn]

Np! You'll get to this point too! This is mostly basics, so you should hopefully feel just as comfortable in a few short months

[royal flare]

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