| Re: referencing structure arrays [message #68007 is a reply to message #68004] |
Thu, 10 September 2009 09:36   |
penteado
Messages: 866
Registered: February 2018
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On Sep 10, 1:12 pm, niv <nivedita.raghun...@gmail.com> wrote:
> Sorry, looks like what I typed looks gibberish in places. I hope this
> one is more readable:
>
> Hi All,
>
> I have a problem referencing structure arrays and assigning values to
> them. So here is a snippet of my code:
>
> junk1=update_state(junk) ;creates a structure called junk1
> statearr=replicate(junk1,3) ;creates an array of structures
>
> infoptr=ptr_new({statearr:statearr}) ;need this to pass variables
> between programs
>
> align_images,state=state1 ;some program that aligns 2 images and
> stores the alignment results in state1
>
> ;assign values from the state1 structure to infoptr.statearr[0]
> structure
> (*infoptr).statearr[0].resvol_file_ptr=state1.resvol_file_pt r
> (*infoptr).statearr[0].air_file_ptr=state1.air_file_ptr
>
> Now, here is the problem. With the above code, it turns out that...
>
> (*infoptr).statearr[0].resvol_file_ptr, (*infoptr).statearr
> [1].resvol_file_ptr, (*infoptr).statearr[2].resvol_file_ptr
> all have the same values. Similarly with air_file_ptr. Even though I
> haven't assigned anything to the statearr 1 and 2 yet.
>
> Is there a specific way to reference these structure arrays? Any help
> is greatly appreciated!
>
> Thanks
> Niv
If I read it right, it sounds like state1.resvol_file_ptr is not a
scalar, but is an array with 3 elements. Check it with n_elements
(state1.resvol_file_ptr). Put it another way, I think what is
happening is the same as
IDL> a=intarr(3)
IDL> print,a
0 0 0
IDL> b=[1,1,1]
IDL> a[0]=b
IDL> print,a
1 1 1
Which is that way because if you use an array element on the left side
of an assignment, and assign to it an array with N elements, then N
elements are assigned, starting at the one given on the left side.
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