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The following table shows Visual Basic data types that correspond to DTWAIN data types (32-bit applications).
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DTWAIN Data Type
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VB .NET Type
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Visual Basic 6.0 and below
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DTWAIN_ARRAY
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Integer
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Long
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DTWAIN_CALLBACK_PROC
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Delegate
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Long
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DTWAIN_BOOL
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Integer
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Long
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DTWAIN_FLOAT
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Double
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Double
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DTWAIN_FRAME
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Integer
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Long
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DTWAIN_OCRENGINE
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Integer
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Long
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DTWAIN_PDFTEXTELEMENT
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Integer
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Long
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DTWAIN_RANGE
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Integer
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Long
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DTWAIN_SOURCE
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Integer
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Long
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HANDLE
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Integer
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Long
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LONG, DTWAIN_LONG
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Integer
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Long
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DTWAIN_LONG64
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Long
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Not available
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LPCTSTR
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String
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String
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LPDTWAIN_ARRAY
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Integer (passed ByRef)
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Long (passed ByRef)
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LPDTWAIN_FLOAT
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double (passed ByRef)
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Long (passed ByRef)
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LPLONG
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Integer (passed ByRef)
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Long (passed ByRef)
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LPTSTR
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String
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String
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LPVOID
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Integer (passed ByRef)
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Long (passed ByRef)
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TWAIN_IDENTITY
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Integer
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Long
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•
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VB .NET/2005/2008/2010 considers 32-bit types as Integer, while DTWAIN considers 32-bit types LONG. Make sure that when declaring a LONG type variable in VB .NET, you actually declare the variable as /nteger. For a 64-bit types, the Long data type of VB.NET is a 64-bit integer type.
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•
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For VB .NET/2005/2008/2010, DTWAIN_SetCallback must use a delegate as the function pointer argument. Delegates are discussed in most VB .NET/2005/2008/2010 books, tutorials, etc. so it will not be discussed here except to state that delegates are VB .NET/2005/2008/2010 equivalent to a function pointer.
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For 64-bit applications, the VB.NET/2005/2008/2010 types are as follows:
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DTWAIN Data Type
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VB .NET Type
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DTWAIN_ARRAY
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Long
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DTWAIN_CALLBACK_PROC
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Delegate
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DTWAIN_BOOL
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Long
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DTWAIN_FLOAT
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Double
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DTWAIN_FRAME
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Long
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DTWAIN_OCRENGINE
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Long
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DTWAIN_PDFTEXTELEMENT
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Long
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DTWAIN_RANGE
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Long
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DTWAIN_SOURCE
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Long
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HANDLE
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Long
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LONG, DTWAIN_LONG
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Integer
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DTWAIN_LONG64
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Long
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LPCTSTR
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String
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LPDTWAIN_ARRAY
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Long (passed ByRef)
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LPDTWAIN_FLOAT
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double (passed ByRef)
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LPLONG
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Integer (passed ByRef)
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LPTSTR
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String
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LPVOID
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Integer (passed ByRef)
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TWAIN_IDENTITY
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Long
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