why there is no error for a= [10,] but error for [10,,] in python?

Question

why is there no error for a = [10,] but error for [10,,] in Python ?
what is interpreter expecting from comma/s in both the cases?

I understand it's more of a syntax error but there has to rationale/logical explanation of this.

It's just a syntax error... I don't know what you are expecting as an explanation. — j1-lee, Nov 05 '22 at 03:52
Does this answer your question? [Why are trailing commas allowed in a list?](https://stackoverflow.com/questions/11597901/why-are-trailing-commas-allowed-in-a-list) — S.B, Nov 05 '22 at 06:46

score 2 · Answer 1 · answered Nov 05 '22 at 03:59

2

Of course there is a logical explanation.

Many people, when writing a list, leave in the extra final comma, as in

lst = [1,2,3,4,]

So, Python allows that and ignores a final comma. But you can't have an empty entry in the MIDDLE of a list.

answered Nov 05 '22 at 03:59

Tim Roberts

+1. Especially when they write their list vertically. *Black* also formats long lists vertically with a trailing comma. – S.B Nov 05 '22 at 06:44

score 0 · Answer 2 · answered Nov 05 '22 at 06:24

In python list we cannot have an empty entry in middle of two values. We need to put either any value of any datatype or None.

-->In this the pyhton will ignore the last comma as no value is after that.

lst = [10,20,30,]

--> It shows there is an empty entry before the end of list and its not permissible. Thats why it will throw an error.

lst = [10,,]

2 Answers2