Python: setting two variable values separated by comma in python

Question

Python: setting two variable values separated by comma in python

What is the difference between python between:

a, b = c, max(a, b)

and

a = c
b = max(a, b)

what does having two variable assignments set on the same line do?

+3

python variable-assignment python-2.7

farid99 22 jul. 15 at 14:45

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2 answers

They are different. The second is to do it

a, b = c, max(c, b)

because before b = max(a, b)

you assign c

to a

. Whereas the former uses the old value a

to calculate it.

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Assem Chelli 22 jul. 15 at 14:57

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Alex Riley · Accepted Answer · 2015-07-22T14:54:12+0000

Your two snippets do different things: try with a

, b

and c

equal 7

, 8

and 9

respectively.

The first snippet sets three variables in 9

, 8

and 9

. In other words, it is max(a, b)

evaluated before being a

assigned to a value c

. Basically, all it a, b = c, max(a, b)

does is push two values onto the stack; variables a

and b

then assigned to these values when discarded.

On the other hand, running the second snippet sets all three variables to 9

. This is because it is a

set to a value c

before calling the function max(a, b)

.

Python: setting two variable values ​​separated by comma in python

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Python: setting two variable values separated by comma in python