What is in (.) mean?

[#1]

trying to understand my mate's code. I have never seen this before but what does in (.) mean?

[#2]

if adj_fac not in (.)

is equal to

if adj_fac ne .

Maybe someone did not remember the mnemonic for "not equal" 😉

[#3]

I see. why not just not missing? so much easier to read.

[#4]

not missing(adj_fac)

works too. There are many ways to do this.

[#5]

..or:

if adj_fac > .z then ...

🙂

Bart

[#6]

if adj_fac ne .

is less typing than

if not missing(adj_fac)

Good programmers are lazy (Linus Torvalds) 🙂

[#7]

But those two are not equivalent.

1    data test;
2      adj_fac = .B;
3      if adj_fac ne . then x1=1;
4      if not missing(adj_fac) then x2=1;
5      put _all_;
6    run;

adj_fac=B x1=1 x2=. _ERROR_=0 _N_=1

Bart

[#8]

---

@Nietzsche wrote:

I see. why not just not missing? so much easier to read.

---

For any question relating to "WHY" you must ask the programmer.

I can see a scenario where a prior version of the programming used a list of values with or without the missing. Then needs changed and the list was reduced or replaced leaving the . as the only list.

I have code where I have some code like " IN ('one value') " instead of "variable = 'one value' " because history has shown me that I am very likely to have to add values.

[#9]

They probably used to have other values in the list of excluded values.

if adj_fac not in (. 0 -1 999) then ...

And they removed the others and did not bother to change from the IN operator to equality operator once there was only one value left in the list.

[#10]

it means adj_fac was not missing. I wouldn't have written it that way. I prefer the missing function like others have mentioned here.