# Select a part of a function's result

**URL:** <https://fortran-lang.discourse.group/t/select-a-part-of-a-functions-result/10504>\
**Category:** Tutorials\
**Created:** [November 18, 2025, 1:05pm UTC](https://fortran-lang.discourse.group/t/select-a-part-of-a-functions-result/10504 "2025-11-18T13:05:09Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Arjen](https://avatars.discourse-cdn.com/v4/letter/a/b9bd4f/32.png) [@Arjen](https://fortran-lang.discourse.group/u/Arjen)\
**Post date:** [November 18, 2025, 1:05pm UTC](https://fortran-lang.discourse.group/t/select-a-part-of-a-functions-result/10504/1 "2025-11-18T13:05:09Z")

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I was inspired by @rouson et al.‘s paper on “Julienne” for this little program. It shows how you can select a part of the result of a function without first explicitly storing it. You cannot do:

`x = func_returning_array(n,m)(1)`

where the function returns an array of data (or a derived type of which you only need a small part). But what you can do is this:

```auto

program select_array
implicit none

integer :: n

n = 10

associate( f => get_series(n) )
    write(*,*) f(1), f(size(f))
end associate

contains
function get_series( n ) result(series)
integer, intent(in) :: n
integer, allocatable :: series(

integer :: i

series = [(i, i = 1,n)]

end function get_series
end program select_array

```

The ASSOCIATE construct lets you access the function’s result as if it was a regular array, stored in a separate variable.

Whether this is useful except in special cases, I do not know, but it was amusing enough 😇 .

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**Author:** ![RonShepard](https://avatars.discourse-cdn.com/v4/letter/r/a3d4f5/32.png) [@RonShepard](https://fortran-lang.discourse.group/u/RonShepard)\
**Post date:** [November 18, 2025, 5:22pm UTC](https://fortran-lang.discourse.group/t/select-a-part-of-a-functions-result/10504/2 "2025-11-18T17:22:24Z")

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> [@Arjen](#):
>
> The ASSOCIATE construct lets you access the function’s result as if it was a regular array, stored in a separate variable.

The associate construct works as if you are making a subroutine call where `f` is the dummy argument associated with the actual argument `get_series(n)` evaluated as an expression. So the compiler is evaluating that expression and making a temporary copy for you. That temporary copy dissappears after the end of the block, just like a dummy argument disappears after the procedure returns. I think the same thing could be done with a block statement with the declaration `integer :: f(n)`. I’m not sure if the allocatable attribute is required (in either the procedure or the block) – maybe the temporary array is in the heap with it but on the stack without it?

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**Author:** ![Arjen](https://avatars.discourse-cdn.com/v4/letter/a/b9bd4f/32.png) [@Arjen](https://fortran-lang.discourse.group/u/Arjen)\
**Post date:** [November 19, 2025, 7:48am UTC](https://fortran-lang.discourse.group/t/select-a-part-of-a-functions-result/10504/3 "2025-11-19T07:48:30Z")

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The allocatable attribute is there only to make it possible to return an array of varying size, it could indeed be done simpler, using an automatic array. But what I found enlightening is that you do not need to epxlicitly store the function’s result to get at parts of that result.