def foo(a, b):
a = 1
b[0] = 2
p, q = 100, [200, 300]
foo(p, q)
print(p, q)
>>> 100 [2, 300]
My question is that, why q changes, but p does not? Thank you!
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Wenting.W
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Did you expect `b` to be copied? It's not, all names are references. See the duplicate on how this works. Or see [How to clone or copy a list?](//stackoverflow.com/q/2612802) to create a copy. – Martijn Pieters May 25 '17 at 11:08
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Before putting your questions here, please search for the similar. There are too many similar questions, you can have answers from them – Jay Parikh May 25 '17 at 11:12
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Thanks a lot. I have tried searching but used the wrong keywords. – Wenting.W May 25 '17 at 14:23
1 Answers
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q is a list therefore is "passed by reference" to the function. p is passed by value.
sophros
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As a token of appreciation please upvote the answer when you find it helpful. – sophros May 25 '17 at 14:24