Marshal.SizeOF

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  • Dennis
    #1

    Marshal.SizeOF

    I have a structure:
    <StructLayout(L ayoutKind.Seque ntial)> Friend Structure KEYBDINPUT
    Dim wVK As Byte
    Dim wScan As Byte
    Dim dwFlags As Integer
    Dim time As Integer
    Dim dwExtraInfo As Integer
    End Structure
    dim k as KEYBDINPUT
    When I use Marshal.sizeof( k), I get the size 16 whidh is two more bytes than
    the structure but when I use Len(k), I get the correct number of 14. What is
    going on? I'm confused
    --
    Dennis in Houston
    Tags: None
    • Herfried K. Wagner [MVP]
      #2
      Re: Marshal.SizeOF

      "Dennis" <Dennis@discuss ions.microsoft. com> schrieb:[color=blue]
      >I have a structure:
      > <StructLayout(L ayoutKind.Seque ntial)> Friend Structure KEYBDINPUT
      > Dim wVK As Byte
      > Dim wScan As Byte
      > Dim dwFlags As Integer
      > Dim time As Integer
      > Dim dwExtraInfo As Integer
      > End Structure
      > dim k as KEYBDINPUT
      > When I use Marshal.sizeof( k), I get the size 16 whidh is two more bytes
      > than
      > the structure but when I use Len(k), I get the correct number of 14. What
      > is
      > going on? I'm confused[/color]


      Structure members are aligned at 'DWORD' boundaries:

      1: 'wVK'
      2: 'wScan'
      3--4: Empty
      4--8: 'dwFlags'
      8--12: 'time'
      12--16: 'dwExtraInfo'

      You can control the packing by specifying a value for 'Pack' in
      'StructLayout':

      \\\
      <StructLayout(L ayoutKind.Seque ntial, Pack:=1)> _
      ...
      ///

      For unmanaged structures the default packing size is 4, which is most common
      in the Win32 API (with some exceptions like 'SHFILEOPSTRUCT ').

      --
      M S Herfried K. Wagner
      M V P <URL:http://dotnet.mvps.org/>
      V B <URL:http://classicvb.org/petition/>

        Comment

        • Dennis
          #3
          Re: Marshal.SizeOF

          Thanks...I learn something everyday from you on this newsgroup.

          --
          Dennis in Houston


          "Herfried K. Wagner [MVP]" wrote:
          [color=blue]
          > "Dennis" <Dennis@discuss ions.microsoft. com> schrieb:[color=green]
          > >I have a structure:
          > > <StructLayout(L ayoutKind.Seque ntial)> Friend Structure KEYBDINPUT
          > > Dim wVK As Byte
          > > Dim wScan As Byte
          > > Dim dwFlags As Integer
          > > Dim time As Integer
          > > Dim dwExtraInfo As Integer
          > > End Structure
          > > dim k as KEYBDINPUT
          > > When I use Marshal.sizeof( k), I get the size 16 whidh is two more bytes
          > > than
          > > the structure but when I use Len(k), I get the correct number of 14. What
          > > is
          > > going on? I'm confused[/color]
          >
          >
          > Structure members are aligned at 'DWORD' boundaries:
          >
          > 1: 'wVK'
          > 2: 'wScan'
          > 3--4: Empty
          > 4--8: 'dwFlags'
          > 8--12: 'time'
          > 12--16: 'dwExtraInfo'
          >
          > You can control the packing by specifying a value for 'Pack' in
          > 'StructLayout':
          >
          > \\\
          > <StructLayout(L ayoutKind.Seque ntial, Pack:=1)> _
          > ...
          > ///
          >
          > For unmanaged structures the default packing size is 4, which is most common
          > in the Win32 API (with some exceptions like 'SHFILEOPSTRUCT ').
          >
          > --
          > M S Herfried K. Wagner
          > M V P <URL:http://dotnet.mvps.org/>
          > V B <URL:http://classicvb.org/petition/>
          >
          >[/color]

            Comment

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