CODEWITHSUNDEEP
python
Aditya Malviya
Aditya Malviya

Reputation: 2140

Declare multiple variable in a single line in python

I've code, var a,b,c,d;

I need to rewrite this in python. I'm not sure, since I'm new to python, how to define multiple variables in a sinlge line with no assignment.

I thought of doing 

> a=None 
> b=None 
> c=None 
> d=None

But it should be in one line

Upvotes: 5

Views: 16561

Answers (4)

DaveL17
DaveL17

Reputation: 2016

The "to a single value" part warrants a little bit of extra explanation.

a = b = c = d = None
a = 1
print(b)

>>> None

The above statement does set the value of each variable to None, but with some other types of values, this may not always be the case. Python is an object-oriented language and if you replace the value None with another type of value that is a Python object you might get results that you don't expect (because Python sets all four variables to literally the same object). Consider:

a = b = c = d = list()
a.append(1)
print(b)

>>>[1]

The reason that the result is different is because a, b, c, and d are all referring to the same list. This is a fundamental concept in Python and a really important one to remember, and shows why making these types of one-line declarations can be potentially problematic.

As others have said, declaring your variables on the go (as you need them) is probably the better way to go overall, as it helps to avoid these types of "less obvious" declaration issues.

Upvotes: 3

Aditya Malviya
Aditya Malviya

Reputation: 2140

This will do it in a single line and several expressions

a=None; b=None; c=None; d=None

This will do it in a single line declaring all vars at once with the same value

a = b = c = d = None

And as pointed out in comments, you could even do it with 0 line since you can just use your vars on the go without prior declaration.

Upvotes: 0

Zeeshan
Zeeshan

Reputation: 1166

More pythonic way is tuple unpacking:

a, b, c, d = 1, 2, 3, 4

Or if you want to initialize to single value

a = b = c = d = 1

You could also use semi-colon (although not encouraged)

a=1; b=2; c=3; d=4

All of them would work.

Upvotes: 16

Joe Halliwell
Joe Halliwell

Reputation: 1177

You could use tuple unpacking:

a, b, c = 1, 2, 3

But to be honest, it would more Pythonic to do the assignments on separate lines.

Upvotes: 6

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