Swap 2 Variables in Python

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In Python, it‘s concise, easy and faster to swap 2 variables compared in other Programming languages:

Python:

x, y = y, x

Other programming languages:

temp = x
x = y
y = temp

Actually, we can also use the second method just like the other programming languages, but it‘s

slower than the firt method. Why? Let‘s take a look at the following codes:

>>> x = 1
>>> y = 2
>>> x
1
>>> y
2
>>> id(x)
160123056
>>> id(y)
160123044
>>> x, y = y, x
>>> x
2
>>> y
1
>>> id(x)
160123044
>>> id(y)
160123056

>>> x = 1
>>> y = 2
>>> x
1
>>> y
2
>>> id(x)
160123056
>>> id(y)
160123044
>>> temp = x
>>> id(temp)
160123056
>>> x = y
>>> y = temp
>>> id(x)
160123044
>>> id(y)
160123056
>>> x
2
>>> y
1

As we can see the codes above, the second method involves a new variables ‘temp‘ while the first method not,

so the second method is slower than the first method.

Swap 2 Variables in Python

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原文地址：http://www.cnblogs.com/lxw0109/p/swap_variables.html