Append reference assignment problem handling for list in Python

When assigning values between objects in Python is passed by reference, the copy module in the standard library is required if the object needs to be copied.

1. Copy.copy a shallow copy copies only the parent object and does not copy the inner sub-objects of the object.

2. Copy.deepcopy deep copy Copy object and its sub-object Program:

Import copy  a = [1, 2, 3, 4, [' A ', ' B ']] #原始对象    b = A #赋值, reference to the object  C = copy.copy (a) #对象拷贝, shallow copy  d = Copy.deepco PY (a) #对象拷贝, deep copy    a.append (5) #修改对象a  a[4].append (' C ') #修改对象a中的 [' A ', ' B '] Array object    print ' A = ', a  print ' B = ' , b  print ' c = ', C  

Output Result:

A = [1, 2, 3, 4, [' A ', ' B ', ' C '], 5]
b = [1, 2, 3, 4, [' A ', ' B ', ' C '], 5]
c = [1, 2, 3, 4, [' A ', ' B ', ' C ']]
D = [1, 2, 3, 4, [' A ', ' B ']]

Append reference assignment problem handling for list in Python