🔒 python beginner's question

[cobalt valve]

can someone explain the necessity of using 'try' and exception commands? Because right now, I am thinking that these commands can just be altered by while loop or 'if' statement (such as if non integer / input == zero, print something like that)

[dusk tide]

@cobalt valve

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[meager skiff]

if you do "if non integer" then you can not instantly cast the input to an int. but yes for validating user input try-except is not necessary you can get the input as a string do all validation checks and then convert it and work with it

but there are things where it could be that an error occurs but you do not know if the error occurs. like when you want to open a file but it could be that the programme has no permission to open it or it could not exists so you need to handle that

[lunar lark]

In Python, there exists the adage, "It's easier to ask for permission than forgiveness."

try/except is asking permission, if / else is asking permission.

For applicable situations, the code you write when applying a try / except pattern will often be more concise than applying an if / else pattern.

[cobalt valve]

oh

[oblique wasp]

(it's the other way around actually; also the next message repeats permission)

[white coral]

this will help you out https://realpython.com/python-lbyl-vs-eafp/

[tender yacht]

the point is so the program will keep running/not crash even if it runs into errors

however you need to get the error first in order to know which ones to "except"

[lunar lark]

things = 'Apples', 'Oranges', 'Pears'
index = 9001
if index < len(things):  # Doesn't even cover all IndexError cases!
    print(things[index])
else:
    print('No.')```
vs
```py
things = 'Apples', 'Oranges', 'Pears'
index = 9001
try:
    print(things[index])
except IndexError:
    print('No.')```

The Look Before You Leap pattern involves writing tests, which can get involved.

The Asking Forgiveness pattern lets you just specify the kinds of exceptions you expect could happen.

[cobalt valve]

ohhh

I see

thank you guys

[dusk tide]

Python help channel closed

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🔒 python beginner's question