不可变容器对象的本质:一旦创建后,长度就被唯一确定。但是,对于list而言,长度会有增有减,所以它是可变的。
mutable : list ,dict inmutable : int , string , float ,tuple... mutable和immutable 字面意思理解就是说数据可变和数据不可变 由于python的变量(variable)不需要声明,而在赋值的时候,变量可以重新赋值为任意值,这就涉及到Python的一个重要的核心概念:动态类型(dynamic typing) 在这里重复强调一下在python中一切...
Python Copy In this case, the original list was changed. You can avoid this by creating a shallow copy of the list. Solution: Using Shallow Copying When you create a shallow copy of an object, Python creates a new object and inserts references to the objects found in the original. This ...
/usr/bin/python# -*- coding: UTF-8 -*- # 可写函数说明def changeme( mylist ): "修改传入的列表" mylist.append([1,2,3,4]); print "函数内取值: ", mylist return # 调用changeme函数mylist = [10,20,30];changeme( mylist );print "函数外取值: ", mylist 实例中传入函数的和在末尾...
到这里为止,明白了mutable和immutable对象的区别,再来看最开始的initList函数 definitList(a, n, l =[]):foriinrange(n): l.append(a)returnl 因为python只编译函数一次,并且会把参数默认初始值也保存下来,所以实际上在编译函数的时候,l = []指向了内存中的某个位置,后边的l.append操作并不会改变这个l所...
Examples of mutable data types in Python include: list: Lists are ordered collections that can be modified by adding, removing, or changing elements. dict: Dictionaries are collections of key-value pairs, and we can add, remove, or modify items using their keys. ...
因为在python的世界里,int 是immutable的 (以及float , str, tuple 这些),也就是一旦赋值了,就不会改变,如果改变,under the hood 他们是重新造了一个obj 来存放新的int。[0] * n 相当于有n个int,每个都独立。 但是list不同,他是mutable的,可以理解成只有一个地方放这个东西,如果做了改变,就是在原有基础...
列表(list):是由多个值组成的序列,Python中最有用的内置类型之一; 元素(element):列表中的值,也称为项(item); 1、列表是一个序列 在列表中,值可以是任何数据类型,同一也不需要是相同的数据类型,一个不包含元素的列表被称为空列表; 创建新列表的方法最简单的是用方括号( [ 和 ] )将元素包括起来; ...
For example, lists are mutable in Python: int_list = [4, 9] int_list[0] = 1 # int_list is now [1, 9] Python 2.7 And tuples are immutable: int_tuple = (4, 9) int_tuple[0] = 1 # Raises: TypeError: 'tuple' object does not support item assignment Python 2.7 String...
Immutable is the when no change is possible over time. In Python, if the value of an object cannot be changed over time, then it is known as immutable. Once created, the value of these objects is permanent. List of Mutable and Immutable objects ...