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'ReDim PRESERVE' Multidimensional Array?

I read in the vb docs that when i use the PRESERVE keyword with multidimensional arrays that ONLY the last dimension is allowed to be altered. For example:
Create the Array:
Dim Test()
ReDim Test(0 to 10, 0 to 10, 0 to 10)
-------
Now Resize it:
ReDim PRESERVE Test(0 to 10, 0 to 10, 0 to 50)
This is CORRECT
--------
Now, here is an error:
ReDim PRESERVE Test(0 to 10, 0 to 50, 0 to 10)

Notice how the 2nd dimension was changed from "0 to 10" to "0 to 50" this is absolutely not allowed in VB. It is documented.

What i want to know is what a good workaround is so as to KEEP my same array but some how change that 2nd dimension size but still maintaining my content.

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ljaques
Asked:
ljaques
1 Solution
 
MirkwoodCommented:
Why not change the order of what you are storing in the variant.

So instead of myvar(i,j,k) you access it like myvar(i,k,j) and now you can preserve everything and modify the last one.
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cognitionCommented:
A user defined type can contain a dynamic array. So you could use the following

Type MyTypeArray
    ArrayX()
    ArrayY()
    ArrayZ()
End Type

and then even hold the MyTypearray in another array.

Or you could use a class that has three arrays.
Or a collection that holds MyTypeArray's

Dim MyColection as new collection
MyCollection.add
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amebaCommented:
>a good workaround
VB is 'good' only with 1D arrays. Use 2 or more dimensions and forget speed and good memory handling.
To speed up redimensioning or copying array portions you can use VarPtr and APIs CopyMemory/ZeroMemory. Try searching Internet for samples and references, e.g. VBPJ has nice articles/samples.
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ljaquesAuthor Commented:
mirkwood,
  I forgot to mention....There are "two" dimensions that i want to varying their sizes not "one" as was demonstrated in my original example. So, if i tried to flip the order of my dimensions i would solve one's resizing problem but would be stuck with the other. ie. myvar(i,j,k) where j and k can vary in size.
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MirkwoodCommented:
What do you expect it do when resizing two dimensions with keeping the data?


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cognitionCommented:
I beleive you can do that with my example.

Redim Preserve MyArray.Array1(1 to 10)
Redim Preserve MyArray.Array2(1 to 20)
Redim Preserve MyArray.Array3(1 to 30)

Then

Redim Preserve MyArray.Array1(1 to 40)
Redim Preserve MyArray.Array2(1 to 50)
Redim Preserve MyArray.Array3(1 to 60)

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MirkwoodCommented:
cognition: Your example stores 10+20+30 values = 60
While Test(1 to 10, 1 to 20, 1 to 30) = 10*20*30 values = 6000 values.

ljaques:
What do you expect it do when resizing two dimensions with keeping the data?  


 
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