本文共 1974 字，大约阅读时间需要 6 分钟。

Operators

• 取整 double slash //

  = math.floor()

• 取余 percentage / modulus operator %

• 逻辑运算符：

  · And: &
  · Or: |
  · XOR: ^
  计算过程：将数字换算成二进制后，每一位分别进行逻辑XOR的运算
  6 ^ 2
  2 = 1 0
  6 = 1 1 0
  ————
  == 1 0 0 =》 4

• ord() 中间放字符，可以显示该字母的unicode码，如ord(a) = 97

• chr(97) = ‘a’, 是ord()的反向

Functions

• eval()
  将string转化为float或int。

eval("4.05")4.05  # floateval("3 + 4")7  # int

• capitalize()
  将整句的第一个单词首字母变为大写。

Shallow Copy & Deep Copy

python中copy()函数与list[ : ]使用的就是shallow copy，当original list只有一层结构没有嵌套时，不会有什么问题，对新list的更改并不会改变老list。

import copy## shallow copyoriginal_list = [1, 2, [3,5], 4] new_list = copy.copy(original_list)  # 将new_list中的3 改变为 7 后：The original elements before shallow copying1 2 [3, 5] 4 The original elements after shallow copying1 2 [7, 5] 4 ## deep copyoriginal_list = [1, 2, [3,5], 4] new_list = copy.deepcopy(original_list) # 将new_list中的3 改变为 7 后：The new list of elements after deep copying 1 2 [7, 5] 4 The original elements after deep copying1 2 [3, 5] 4

以下内容是更详细的解释，援引自下面的网址

• Deep copy is a process in which the copying process occurs recursively. It means first constructing a new collection object and then recursively populating it with copies of the child objects found in the original. In case of deep copy, a copy of object is copied in other object. It means that any changes made to a copy of object do not reflect in the original object. In python, this is implemented using “deepcopy()” function.

• A shallow copy means constructing a new collection object and then populating it with references to the child objects found in the original. The copying process does not recurse and therefore won’t create copies of the child objects themselves. In case of shallow copy, a reference of object is copied in other object. It means that any changes made to a copy of object do reflect in the original object. In python, this is implemented using “copy()” function.

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