Consider the following Python code, if the run ends, what is the result of the run on the command line?

Source: Internet
Author: User
Tags shallow copy

1 1. L = []2 for in xrange:3 3.     L.append ({' num ': i})4print l
1 1. L = []2 2. A = {' num ': 0}3 for in Xrange ():4 4.     a[' num '] = i5 5.     L.append (a)6print l

Are the two sections of code running the same, if not the same, what are the reasons?

The result of the above code:

1 1. [{' num ': 0},{' num ': 1},{' num ': 2},{' num ': 3},{' num ': 4},{' num ': 5},{' num ': 6},{' num ': 7},{' num ': 8},2 {' num ': 9}]

The result of the code below:

1 1. [{' num ': 9},{' num ': 9},{' num ': 9},{' num ': 9},{' num ': 9},{' num ': 9},{' num ': 9},{' num ': 9},{' num ': 9},2 {' num ': 9}]

So here's the reason:

The reason is that the dictionary is a mutable object, and in the operation of L.append (a) below, the reference to dictionary A is passed to the list L, when
Continue to modify the value of a[' num '), the value in L will also change, equivalent to a shallow copy.

Consider the following Python code, if the run ends, what is the result of the run on the command line?

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