8/2(2+2) doesn't work in python but 8/2+(2+2) and 8/2*(2+2) do. Why?

Question

Trying to understand operands in python.

8/2(2+2) gave the following error:

TypeError Traceback (most recent call last)
<ipython-input-12-8949a58e2cfa> in <module>
----> 1 8/2(2 + 2)

TypeError: 'int' object is not callable.

Trying to do this like this then using sum() then as python dictionary then in numpy.

`8/2(2 + 2)` first tries to *call* `2(2 + 2)`, trying to treat `2` like a function. But `int` objects are not callable. Hence the error. You meant `8/2*(2 + 2)` — juanpa.arrivillaga, Oct 20 '21 at 19:30
@juanpa.arrivillaga your first sentence answers my question perfectly thank you. — Shakescreen, Oct 20 '21 at 19:42
Clarification: 8/2(2+2) = 1 (or 4 or 16 depending on your calculator!), 8/2+(2+2) = 8 and 8/2*(2+2) = 16. Totally different questions. Does this mean that there is no way to make 8/2(2+2) work in python? — Shakescreen, Oct 20 '21 at 19:51

Joseph Sible-Reinstate Monica · Accepted Answer · 2021-10-20T19:32:31.853

3

Python doesn't support implicit multiplication. When Python tries to run 2(2+2), it tries to call the numeric literal 2 as a function, passing 2+2 as an argument to it. You need to use * between things you want to multiply.

edited Oct 20 '21 at 19:32

answered Oct 20 '21 at 19:29

Joseph Sible-Reinstate Monica

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Well, not to a function with the global variable `2` since `2` isn't a valid identifier, it is still interpreted as an `int` literal – juanpa.arrivillaga Oct 20 '21 at 19:30
Good explanation. Better to mention there cannot be a callable named `2`. Or can there? – MSH Oct 20 '21 at 19:32
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@juanpa.arrivillaga Does the new wording make that more clear? – Joseph Sible-Reinstate Monica Oct 20 '21 at 19:32
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Yep, it's a pedantic point but since we are talking about how the grammar is parsed I feel it is relevant – juanpa.arrivillaga Oct 20 '21 at 19:34

Mandraenke · Answer 2 · 2021-10-20T19:35:22.077

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There is no operator between the 2 and the ( - human math assumes a multiplication here but a computer does not.

The parser sees 2(...) - which is interpreted as a function with the name 2 and a parameter.

Since there is no default function with that name and there is no def 2(x) you get that error message.

Additionally 2 is not a vaild function name in python.

edited Oct 20 '21 at 19:35

answered Oct 20 '21 at 19:32

Mandraenke

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Well, *python specifically* works this way. Another programming language could support implicit multiplication. I mean, the *computer* doesn't understand any of that at all, it understands machine code – juanpa.arrivillaga Oct 20 '21 at 19:35

score 1 · Answer 3 · answered Oct 20 '21 at 19:36

Python doesn't work like normal maths. 2(2+2) will not be executed as 2×4. Instead, 2 will be treated as a function, which is not callable (your error message) . To do that, you've to put operator between 2 and (2+2). Try putting a * between 2 and (2+2). Your expression would be 8/2*(2+2)

8/2(2+2) doesn't work in python but 8/2+(2+2) and 8/2*(2+2) do. Why?

3 Answers3