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CopyMemory and Arrays: Proper Use

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  9 years ago

  by Developer Fusion Bot

  Developer Fusion Bot

  , United Kingdom

  Joined 2 years ago

  This thread is for discussions of CopyMemory and Arrays: Proper Use.

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  5 years ago

  by BitShifter

  Richard Jalbert

  Montreal, CANADA, Canada

  Joined 5 years ago

  I'm willing to bet that if he first variable in the UDT had been an integer, the following Bytes would have been padded to WORD size and no more.
  

  
  This being the start of the week-end, I'll play with this later...

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  5 years ago

  by webjose

  Jose Pablo Ramirez Vargas

  Costa Rica, United States

  Joined 6 years ago

  I just tested and yes, you are correct.
  

  
  Private Type MyType
     var1 As Integer
     var2 As Byte
     var3 As Boolean
  End Type
  

  
  The above type will get padded to a WORD, not a DWORD.  However, starting with a WORD is not enough.  The following will get DWORD-aligned, meaning you must not have DWORDS or QWORDS.
  

  
  Private Type MyType
     var1 As Integer
     var2 As Byte
     var3 As Long
  End Type
  

  
  Private Type MyType
     var1 As Integer
     var2 As Byte
     var3 As Double
  End Type
  

  
  Private Type MyType
     var1 As Integer
     var3 As Double
  End Type
  

  
  Thanks for the observation.  I will update the article to add the finding.

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  4 years ago

  by kwadrofonik

  kwadrofonik

  , United States

  Joined 4 years ago

  Thanks. Definately some good information, however...
  

  
  It is not very practical to use the ReDim statement each iteration of a loop since it copies the entire array to a different memory location in order to change the dimension. In fact, using the CopyMemory function for this purpose is useful as well. A good compromise would be to redimension the array every 20th iteration and then check for empty array values, such as:
  

  
  If SubDirCount = UBound(DirList) Then ReDim Preserve DirList(UBound(DirList) + 20)
  

  
  an even better solution is to use an array object.

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