Python中 + 和 += 的区别_python +1=

+= 不会创建新对象，+会创建新对象（针对可变类型）

对可变类型来说，+=不会创建新对象，对不可变类型，+和+=都会创建新对象

>>> a = [1,2]
>>> id(a)
47952136
>>> a += [3,4]
>>> id(a)
47952136 # 结果前后一致
>>> a
[1, 2, 3, 4]
>>> b = [1,2]
>>> id(b)
48147208
>>> b = b + [3,4]
>>> id(b)
48062984 # 不一致
>>> b
[1, 2, 3, 4]
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不能用+连接元组和列表

>>> a = [1,2]
>>> a += (3,4)
>>> a
[1, 2, 3, 4]
>>> b = [1,2]
>>> b = b + [3,4]
>>> b
[1, 2, 3, 4]
>>> b = b + (5,6)
Traceback (most recent call last):
  File "<pyshell#6>", line 1, in <module>
    b = b + (5,6)
TypeError: can only concatenate list (not "tuple") to list
>>> 
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