### 1. The length function

- Posted by dr_can May 06, 2016
- 804 views

The manual indicates that, for example,

length({{1,2}, {3,4}, {5,6}}) -- 3

but what should

length({{}})

return?

The answer is 1, but why is it not 0?

### 2. Re: The length function

- Posted by ghaberek (admin) May 06, 2016
- 785 views

dr_can said...

The answer is 1, but why is it not 0?

Because that sequence contains *one* item: a sequence whose length is zero.

Here's another example:

sequence item1 = {} sequence item2 = {} sequence item3 = {} sequence items = { item1, item2, item3 } ? length( items ) -- contains 3 items

-Greg

### 3. Re: The length function

- Posted by SDPringle May 06, 2016
- 773 views

dr_can said...

The manual indicates that, for example,

length({{1,2}, {3,4}, {5,6}}) -- 3

but what should

length({{}})

return?

The answer is 1, but why is it not 0?

Consider

sequence s1 = {} sequence s2 = {s1} ? length(s2) -- returns 1 ? length(s1) -- returns 0

Now, s2 is a sequence and s2[1] is s1. It is not empty in itself. The sequence s1 is empty however. Finally s2 is equivalent to

{{}}

SD Pringle