for key in dict 和 for key in dict.keys() 它们有什么不一样吗?我看教程好像除了第二种多了 .keys() ,好像没有区别啊?
for key in dict
for key in dict.keys()
x = {'a':'A', 'b':'B'} for key in x: print(key) a b
x = {'a':'A', 'b':'B'} for key in x.keys(): print(key) a b
for key in x 要比 for key in x.keys()快 毕竟少调用了一个函数keys/values/items是dict的三种视图,对应不同的dictiter,适合传递给其他函数遍历同样要获得dictiter_key x.__iter__() 要比 x.keys()__iter__() 更直接
for key in x
for key in x.keys()
x.__iter__()
x.keys()__iter__()
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