#include <MsgBoxConstants.au3>

Example()

Func Example()
        ; Assign a Local constant variable the definition of a structure.
        Local Const $tagSTRUCT1 = "struct;int var1;byte var2;uint var3;char var4[128];endstruct"

        ; Assign a Local variable the structure.
        Local $tSTRUCT1 = DllStructCreate($tagSTRUCT1)

        ; If an error occurred display the error code and return False.
        If @error Then
                MsgBox($MB_SYSTEMMODAL, "", "Error in DllStructCreate, Code: " & @error)
                Return False
        EndIf

        #cs Comments:
        -The default alignment for the data is 4 bytes, thus each element will take at least 4 bytes.
        -The min size can be obtained by setting an alignment of 1 at the beginning of the struct definition: "align 1;struct; ..."

        -Detailed information on the struct size:
        var1: int - 4 bytes
        var2: byte - 1 byte + 3 bytes alignment = 4 bytes
        var3: uint - 4 bytes
        var4: char[128] - 1 * 128 bytes
        #ce

        MsgBox($MB_SYSTEMMODAL, "", "Struct Size: " & DllStructGetSize($tSTRUCT1))
EndFunc   ;==>Example