| Re: pointer and structure stuff ... [message #38175] |
Wed, 25 February 2004 05:59 |
btt
Messages: 345
Registered: December 2000
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Senior Member |
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Ingo Salzmann wrote:
>> Is there a particular reason why you are putting your vectors
>> into a structure? In other words, why aren't your vectors a field
>> of your info structure, rather than in a structure of their own?
>> Pointers to structures are pretty much designed to drive you
>> crazy, what with all the extraneous parentheses needed to get
>> things to work. :-(
>
>
> Well, the reason is that I would like to keep track of many different
> vectors that can be categorised by their purpose ... it seemed handy to
> me to have for example a structure vectors_3d_upper in which all
> concerning stuff is being stored ... unfortunately the ammount of
> elements is being changed sometimes and therefore I would have loved to
> easily update by (*info.vectors_3d_upper).reciprocal_lattice =
> uniquevecors :-(
> Thanks,
> Ingo
>
Hello,
I wonder if this might be a case for using the VECTOR object found on
the RSI User Contribution web site. Or you might roll you own vector
object - it's not too hard to do. These kind of objects readily accept
changes in values and lengths as the need arises, but you don't have to
worry about the details in you application. Then you can store all of
your 'vectors' in a container and place the container in your info
structure.
Cheers,
Ben
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| Re: pointer and structure stuff ... [message #38179 is a reply to message #38175] |
Wed, 25 February 2004 00:19  |
Ingo Salzmann
Messages: 10
Registered: December 2002
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Junior Member |
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> Is there a particular reason why you are putting your vectors
> into a structure? In other words, why aren't your vectors a field
> of your info structure, rather than in a structure of their own?
> Pointers to structures are pretty much designed to drive you
> crazy, what with all the extraneous parentheses needed to get
> things to work. :-(
Well, the reason is that I would like to keep track of many different
vectors that can be categorised by their purpose ... it seemed handy to
me to have for example a structure vectors_3d_upper in which all
concerning stuff is being stored ... unfortunately the ammount of
elements is being changed sometimes and therefore I would have loved to
easily update by (*info.vectors_3d_upper).reciprocal_lattice =
uniquevecors :-(
Thanks,
Ingo
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| Re: pointer and structure stuff ... [message #38201 is a reply to message #38179] |
Tue, 24 February 2004 07:39 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Ingo Salzmann writes:
> Can anybody please help me with the following banal problem ...
>
> IDL> info = {vectors:Ptr_New(vectors)}
> IDL> v1 = Indgen(3,30)
> IDL> *info.vectors = {v1:v1}
> IDL> help, (*info.vectors).v1
> <Expression> INT = Array[3, 30]
>
> IDL> temp = Intarr(3,20)
> IDL> (*info.vectors).v1 = temp
> IDL> help, (*info.vectors).v1
> <Expression> INT = Array[3, 30]
>
> with the first 60 elements zeroed ...
> Can I have IDL resize its variable (*info.vectors).v1 easier than by the
> following statement:
>
> IDL> v1=Intarr((SIZE(temp))[1],(SIZE(temp))[2])
> IDL> *info.vectors = {v1:v1}
> IDL> (*info.vectors).v1 = temp
> IDL> help, (*info.vectors).v1
> <Expression> INT = Array[3, 20]
>
> If dealing with a large ammount of elements stored in the info structure
> this doesn't seem handy to me :-(
No, I wouldn't think so. :-(
Is there a particular reason why you are putting your vectors
into a structure? In other words, why aren't your vectors a field
of your info structure, rather than in a structure of their own?
Pointers to structures are pretty much designed to drive you
crazy, what with all the extraneous parentheses needed to get
things to work. :-(
As a field in your info structure, you could do this:
info = {vectors:Ptr_New(/Allocate_Heap)}
data = Fltarr(3, 30)
*info.vectors = data
newdata = IntArr(2, 20)
*info.vectors = newdata
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting
Coyote's Guide to IDL Programming: http://www.dfanning.com/
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