Marshaling Fixed Length Strings in Structure

[Tom]

I'm trying to pass this structure to a dll:

<StructLayout(L ayoutKind.Seque ntial, CharSet:=CharSe t.Ansi, Pack:=1)> _
Public Structure udtINTER01
<VBFixedString( 8), MarshalAs(Unman agedType.ByValA rray, SizeConst:=8)>
Public action As Char()
<VBFixedString( 7), MarshalAs(Unman agedType.ByValA rray, SizeConst:=7)>
Public equip_key As Char()
<VBFixedString( 256), MarshalAs(Unman agedType.ByValA rray,
SizeConst:=256) > Public message As Char()
<VBFixedString( 512), MarshalAs(Unman agedType.ByValA rray,
SizeConst:=512) > Public filler As Char()
End Structure

When I pass it to my dll I get this message:

An unhandled exception of type 'System.Argumen tException' occured in
Test1.exe
Additional Information: Type could not be marshaled because the length
of an embedded array instance does not match the declared length in the
layout

I reviewed the length of each element of the structure and they all
match the declared lengths.

What does it want??

Tom

[Tom Shelton]

In article <OH************ *@TK2MSFTNGP11. phx.gbl>, Tom wrote:

I'm trying to pass this structure to a dll:

<StructLayout( LayoutKind.Sequ ential, CharSet:=CharSe t.Ansi, Pack:=1)> _
Public Structure udtINTER01
<VBFixedString( 8), MarshalAs(Unman agedType.ByValA rray, SizeConst:=8)>
Public action As Char()
<VBFixedString( 7), MarshalAs(Unman agedType.ByValA rray, SizeConst:=7)>
Public equip_key As Char()
<VBFixedString( 256), MarshalAs(Unman agedType.ByValA rray,
SizeConst:=256) > Public message As Char()
<VBFixedString( 512), MarshalAs(Unman agedType.ByValA rray,
SizeConst:=512) > Public filler As Char()
End Structure

I'm not sure if VBFixedString actually works for Interop. Try changing
it to:

<StructLayout(L ayoutKind.Seque ntial, CharSet:=CharSe t.Ansi, Pack:=1)> _
Public Structure udtINTER01
<MarshalAs(Unma nagedType.ByVal TStr, SizeConst:=8)>
Public Action As String
...
End Structure

Also, make sure that you set the charset expected by the function call
to be Ansi as well.

--
Tom Shelton [MVP]

[Tom]

I'm avoiding ByValTStr because it replaces the last byte of the field
with a null. If there were a way to stop Interop from putting the null
on the end that would be great.

Tom
Tom Shelton wrote:

In article <OH************ *@TK2MSFTNGP11. phx.gbl>, Tom wrote:

I'm trying to pass this structure to a dll:

<StructLayout (LayoutKind.Seq uential, CharSet:=CharSe t.Ansi, Pack:=1)> _
Public Structure udtINTER01
<VBFixedString( 8), MarshalAs(Unman agedType.ByValA rray, SizeConst:=8)>
Public action As Char()
<VBFixedString( 7), MarshalAs(Unman agedType.ByValA rray, SizeConst:=7)>
Public equip_key As Char()
<VBFixedString( 256), MarshalAs(Unman agedType.ByValA rray,
SizeConst:=25 6)> Public message As Char()
<VBFixedString( 512), MarshalAs(Unman agedType.ByValA rray,
SizeConst:=51 2)> Public filler As Char()
End Structure

I'm not sure if VBFixedString actually works for Interop. Try changing
it to:

<StructLayout(L ayoutKind.Seque ntial, CharSet:=CharSe t.Ansi, Pack:=1)> _
Public Structure udtINTER01
<MarshalAs(Unma nagedType.ByVal TStr, SizeConst:=8)>
Public Action As String
...
End Structure

Also, make sure that you set the charset expected by the function call
to be Ansi as well.

[Tom Shelton]

In article <#x************ *@tk2msftngp13. phx.gbl>, Tom wrote:

I'm avoiding ByValTStr because it replaces the last byte of the field
with a null. If there were a way to stop Interop from putting the null
on the end that would be great.

Tom

Then use ByValArray instead if this is a reqirement. The SizeConst
thing still works the same.

--
Tom Shelton [MVP]

[Tom]

That's where I started. When I do I get

An unhandled exception of type 'System.Argumen tException' occured in
Test1.exe
Additional Information: Type could not be marshaled because the length
of an embedded array instance does not match the declared length in the
layout

What does it want?

Tom
Tom Shelton wrote:

In article <#x************ *@tk2msftngp13. phx.gbl>, Tom wrote:

I'm avoiding ByValTStr because it replaces the last byte of the field
with a null. If there were a way to stop Interop from putting the null
on the end that would be great.

Tom

Then use ByValArray instead if this is a reqirement. The SizeConst
thing still works the same.

[Tom Shelton]

On Wed, 28 Jul 2004 09:24:35 -0500, Tom wrote:

That's where I started. When I do I get

An unhandled exception of type 'System.Argumen tException' occured in
Test1.exe
Additional Information: Type could not be marshaled because the length
of an embedded array instance does not match the declared length in the
layout

What does it want?

Tom
Tom Shelton wrote:

In article <#x************ *@tk2msftngp13. phx.gbl>, Tom wrote:

I'm avoiding ByValTStr because it replaces the last byte of the field
with a null. If there were a way to stop Interop from putting the null
on the end that would be great.

Tom

Then use ByValArray instead if this is a reqirement. The SizeConst
thing still works the same.

Aaah, looking back I see that :) What I'm saying is remove the
VBFixedLength string stuff:

<StructLayout(L ayoutKind.Seque ntial, CharSet:=CharSe t.Ansi, Pack:=1)> _
Public Structure udtINTER01
<MarshalAs(Unma nagedType.ByVal Array, SizeConst:=8)> _
Public action As Char()

<MarshalAs(Unma nagedType.ByVal Array, SizeConst:=7)> _
Public equip_key As Char()

<MarshalAs(Unma nagedType.ByVal Array, SizeConst:=256) > _
Public message As Char()

<MarshalAs(Unma nagedType.ByVal Array, SizeConst:=512) > _
Public filler As Char()
End Structure

If for some reason that doesn't work, then you may want to change the type
to byte and then use the System.Text.Enc oding class to convert the members
to and from strings.

--
Tom Shelton [MVP]

[Tom]

Didn't help. I used

System.Text.ASC IIEncoding.ASCI I.GetBytes("Get 1Equp")

to get the text into the byte array and I still get

An unhandled exception of type 'System.Argumen tException' occured in
Test1.exe
Additional Information: Type could not be marshaled because the length
of an embedded array instance does not match the declared length in the
layout

I don't understand in what way embedded array does not match the
declared length in the layout.

Tom
Tom Shelton wrote:

On Wed, 28 Jul 2004 09:24:35 -0500, Tom wrote:

That's where I started. When I do I get

An unhandled exception of type 'System.Argumen tException' occured in
Test1.exe
Additional Information: Type could not be marshaled because the length
of an embedded array instance does not match the declared length in the
layout

What does it want?

Tom
Tom Shelton wrote:

In article <#x************ *@tk2msftngp13. phx.gbl>, Tom wrote:
I'm avoiding ByValTStr because it replaces the last byte of the field
with a null. If there were a way to stop Interop from putting the null
on the end that would be great.

Tom

Then use ByValArray instead if this is a reqirement. The SizeConst
thing still works the same.

Aaah, looking back I see that :) What I'm saying is remove the
VBFixedLength string stuff:

<StructLayout(L ayoutKind.Seque ntial, CharSet:=CharSe t.Ansi, Pack:=1)> _
Public Structure udtINTER01
<MarshalAs(Unma nagedType.ByVal Array, SizeConst:=8)> _
Public action As Char()

<MarshalAs(Unma nagedType.ByVal Array, SizeConst:=7)> _
Public equip_key As Char()

<MarshalAs(Unma nagedType.ByVal Array, SizeConst:=256) > _
Public message As Char()

<MarshalAs(Unma nagedType.ByVal Array, SizeConst:=512) > _
Public filler As Char()
End Structure

If for some reason that doesn't work, then you may want to change the type
to byte and then use the System.Text.Enc oding class to convert the members
to and from strings.