| Re: referencing structure arrays [message #68005 is a reply to message #68004] |
Thu, 10 September 2009 10:02   |
nivedita.raghunath
Messages: 15
Registered: July 2006
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Junior Member |
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On Sep 10, 12:36 pm, pp <pp.pente...@gmail.com> wrote:
> 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 referencingstructurearrays and assigning values to
>> them. So here is a snippet of my code:
>
>> junk1=update_state(junk) ;creates astructurecalled 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 state1structureto 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 thesestructurearrays? 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.
I checked it and thats not the case. state1.resvol_file_ptr is a
scalar. I even assigned a different value:
IDL> *(*infoptr).statearr[0].resvol_file_ptr='junk'
IDL> print,*(*infoptr).statearr[0].resvol_file_ptr
junk
IDL> print,*(*infoptr).statearr[1].resvol_file_ptr
junk
IDL> print,*(*infoptr).statearr[2].resvol_file_ptr
junk
I dont' get it.
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