sorted() function 影响原始列表

Question

I am testing some sorting algorithms by passing a list of strings to them. the structure is like this:

def test(test_case):
    ans = sorted(test_case)
    for f in functs:
        assert f(test_case) == ans

However, I found that test_case is changing all the time (I call test() for once). There is a time I passed ["Test", "String'] to test() and I put print() in my f to catch the input. I found that f received [("Test", "String'), ("Test", "String'), ("Test", "String'), ("Test", "String'), ("Test", "String'), ...] . May I know why this happened and what is the solution for that?

Answer 1

sorted does not affect your original list (ie, it does not sort the list in place), but if you execute the code on the interactive interpreter the output of sorted is going to be printed.
So what you see is the list sorted, followed by the original list.

['a', 'day', 'for', 'have', 'nice', 'reading', 'thanks']
['thanks', 'for', 'reading', 'have', 'a', 'nice', 'day']