python list 重复元素不会覆盖

python list 插入重复元素不会覆盖，见以下测试：

Python 3.10.12 (main) [GCC 11.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> a = [1, 2, 3]
>>> print(a)
[1, 2, 3]
>>> a.append(4)
>>> print(a)
[1, 2, 3, 4]
>>> a.append(2)
>>> print(a)
[1, 2, 3, 4, 2]
>>> a.append('6')
>>> print(a)
[1, 2, 3, 4, 2, '6']
>>> a.append('6')
>>> print(a)
[1, 2, 3, 4, 2, '6', '6']

如果需要重复元素不被添加，需自行判断元素是否存在，见以下demo：

if item not in object_list:
	object_list.append(item)

python 列表基本操作

Python 表达式	结果	描述
len([1, 2, 3])	3	长度
[1, 2, 3] + [4, 5, 6]	[1, 2, 3, 4, 5, 6]	组合
['Hi!'] * 4	['Hi!', 'Hi!', 'Hi!', 'Hi!']	重复
3 in [1, 2, 3]	True	元素是否存在于列表中
for x in [1, 2, 3]: print x,	1 2 3	迭代