CODEWITHSUNDEEP
pythonpython-3.xfor-looppython-2.xconventions
Sssssuppp
Sssssuppp

Reputation: 711

Difference between similar looking Python for-loops?

I was curious about the way this 

for _ in range(10): #1

loop#1 execution is different from 

for i in range(10): #2

loop#2 execution. They certainly do look exactly the same, but, I wanted to have a clear understanding and know if their functioning under the hood is also exactly the same? Also, I know when both these types of loops are used, so, I am not looking for an answer to "When to use What?".

I had already read this question, but, it doesn't provide a clear distinction and the working of the two under the hood.

Upvotes: 1

Views: 46

Answers (2)

Gytree
Gytree

Reputation: 540

in python the underscore character it's a valid var name, so bot snippets are the same but with different var names, like @AK47 says, use de under score if you don't want use the var inside the loop, but the _ it's a valid var name so you can used inside the loop:

enter image description here

some frameworks like django use the underscore in their code patterns:

enter image description here

Upvotes: 1

AlanK
AlanK

Reputation: 9843

They both do the exact same thing

The former is used if the variable is disposable and not usually referenced in the loop

for _ in range(10): #1

The latter is used if you plan to reference the variable name within the loop

for i in range(10): #2

It's boils down to the python naming convention -- under the hood, both loops function in the exact same way

Upvotes: 4

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