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redim preserve an array to a smaller amount

Posted on 2002-03-21
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Last Modified: 2012-06-27
Hi

Im rediming an array to a smaller amount and Im getting an error 'subscript out of range'

eg
dim arr()

'get y
redim preserve arr(y,8)

' catch that arr should be smaller so
''get  x
redim preserve arr(x,8) - this is where I get the error

any ideas??
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Question by:louise_8
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6 Comments
 
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Expert Comment

by:Clif
ID: 6886244
This is a limitation of VB.

According to the help file (for "ReDim Statement"):
"If you use the Preserve keyword, you can resize only the last array dimension and you can't change the number of dimensions at all. For example, if your array has only one dimension, you can resize that dimension because it is the last and only dimension. However, if your array has two or more dimensions, you can change the size of only the last dimension and still preserve the contents of the array. The following example shows how you can increase the size of the last dimension of a dynamic array without erasing any existing data contained in the array."
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Expert Comment

by:ebosscher
ID: 6886813
Clif's got it
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Accepted Solution

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mdougan earned 20 total points
ID: 6886932
Yes, what Clif said is correct.  In your example, you can probably get away with switching the position of the dimensions:

dim arr()

'get y
redim preserve arr(8,y)

' catch that arr should be smaller so
''get  x
redim preserve arr(8,x)

Keep in mind that while the available array elements would be less, you are not actually freeing up any memory by doing this.  The only way memory would get freed for this array is if you :

Dim a temp array the size of your perm array
copy perm array to a temp array
Erase perm array
redim perm array
copy temp array to perm array
erase temp array
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Expert Comment

by:Clif
ID: 6888598
If "Clif's got it" and "what Clif said is correct" then why did the grade and points go to mdougan?
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Expert Comment

by:ebosscher
ID: 6888803
Because mdougan suggested a work around
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Expert Comment

by:Clif
ID: 6888828
Oh.
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