🔒 Why do I need to check if amount is >0 with .isdigit

[unkempt prawn]

I have this piece of code from a yt tutorial from Tech with Tim.
Why do I need to check if the amount is greather than 0 ? Doesnt .isdigit check that alr?

[harsh wadi]

@unkempt prawn

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[tiny hamlet]

It should, ya. It's arguably good to make that check explicit though. It's not clear from amount.isdigit alone that you're also ensuring that the number was positive

[wooden axle]

i would say that it isn't very pythonic to write the code like that
it's preferred to just cast the data with int() and catch the exception
and if it can be converted then check if it is > 0

[unkempt prawn]

So is the code the person in the tutorial wrote bad? Bc im watching the video to learn how to write efficient/good python code if you could call it that

[wooden axle]

anyways, it's missing a colon on the end of the line with the last if statement

[heavy dust]

why? this works perfectly fine

that just seems like a lot more work to me

[tiny hamlet]

A lot of YT tutorials show bad practices. The bar for entry is so low, anyone can make videos.

[heavy dust]

especially for someone who (i assume) is pretty new to python

[unkempt prawn]

Oh, ok

[wooden axle]

at least i don't think it's his specialty

https://realpython.com/python-lbyl-vs-eafp/

[wooden axle]

it kind of works but doesn't take into account other possible valid ways to enter a number

[unkempt prawn]

What does casting the data with int() mean?

[heavy dust]

like?

[wooden axle]

in this instance it's about parsing the string to an integer if possible

[fading flare]

turn it into an integer

[unkempt prawn]

I do that in line 6, right?

[fading flare]

yes

also you're missing a colon

[unkempt prawn]

Is there a more efficient way to do that?

[fading flare]

not really

whats wrong with that method?

also note that int can raise a ValueError if given a non-int string

[heavy dust]

colon*

[fading flare]

[wooden axle]

it depends on if you expect most inputs to be valid numbers or not

[unkempt prawn]

Probably

[wooden axle]

if that is true, then you should just try to cast the string and then catch the exception if it can't

[unkempt prawn]

Alright thank you!

[wooden axle]

def deposit():
    while True:
        try:
            amount = int(input("What would you like to deposit? $"))
            if amount > 0:
                break
            print("The amount must be greater then 0")
        except ValueError:
            print("Input must be a valid integer")
    total += amount

[wooden axle]

untested code above written directly here in the chat on my phone

and it's only partial code, if total is a global variable you would want a global statement at the beginning of the function as well, but i prefer to not use global variables, so consider this a code snippet taken out of its context

[unkempt prawn]

Thank u alot!

[unkempt prawn]

May I ask, in contrast to my code above, what makes this code superior? Is there smth about your code, that prevents errors or smth?

[fading flare]

that's unbound btw

amount will raise an error

just wrap only the int cast and return if it fails

[fading flare]

yours just doesn't catch the ValueError from the int cast

thats basically the only difference

you could check it with str.isdigit

[wooden axle]

as i said, untested and taken out of context, i also tried to conform to how the original function worked (not returning out of the function anywhere), it's not how I would choose to write this myself

[fading flare]

[fading flare]

didnt see this myself because i was on my phone too

[wooden axle]

i would definitely have a small function for this that return the data or an error rather then doing it all in one big function

[unkempt prawn]

But doesnt it check the same thing?

if amount.isdigit():
this checks if the input is a positive number right?

amount = int (amount)
This turns the string into an integer right?

While writing this I believe in realising why your code is different. Your has like a way to handle any other input than s number right? Mine just states that it doesnt need a string or a negative number, but it doesnt handle the case of someone writing a string or a negative number in the input. Am I correct?

[fading flare]

both of your checks are correct, yes

honestly that's really all you need

as long as you dont let int go through if .isdigit fails

[wooden axle]

but .isdigit() may reject valid numbers that int() is able to convert

[unkempt prawn]

For example? Negative Numbers?

[wooden axle]

one example is the string "600_000_000" which int() will handle but be rejected by .isdigit() of you like that or not is another question, but it's easier to read in an instance then "60000000"

hint, u messed that up on purpose 😉

did you catch that? 😁

[wooden axle]

you were asking for a more efficient way
this way you don't need to first check if every character is a number and then convert it
if it was efficiency you were after

[harsh wadi]

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