是否在循环的每次迭代中重新评估range（）的参数？(Are parameters to range() re

是否在循环的每次迭代中重新评估range（）的参数？(Are parameters to range() re-evaluated at each iteration of the loop?)

如果我使用范围参数的函数，他们每次都会被调用吗？

for i in range(min(some_list), max(other_list)): ...

If I use functions for range parameters, do they get called every time through?

for i in range(min(some_list), max(other_list)): ...

最满意答案

通过一个小实验很容易回答你的问题。

In [294]: def foo(n): ...: print('in foo') ...: return n ...: In [295]: for i in range(foo(5)): ...: print(i) ...: in foo 0 1 2 3 4

所以，是的， range参数只被评估一次 ，就像任何其他函数调用的参数一样。

It becomes easy to answer your question with a little experiment.

In [294]: def foo(n): ...: print('in foo') ...: return n ...: In [295]: for i in range(foo(5)): ...: print(i) ...: in foo 0 1 2 3 4

So, yes, the parameters to range are evaluated only once, much like the parameters to any other function call.