interop for string[] array

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Egbert Nierop (MVP for IIS) - 18 Nov 2005 00:44 GMT

The P/I function ADsBuildVarArrayStr works. When I look at the IL, no heavy
Marshal code is done. I even suspect, that a pointer is passed to the array
and that the array even not is pinned.

But when it comes to passing a string[] array through a struct, it does not
work. Are there any secrets? (I'm using .NET 2.0)

sample what I would like to pass to a win32 function

struct blah
{
int cElements;
string [] elements
}

[DllImport("Activeds.dll", SetLastError = false, CharSet = CharSet.Unicode)]

public static extern int ADsBuildVarArrayStr(//
[MarshalAs(UnmanagedType.LPArray, ArraySubType = UnmanagedType.LPWStr)]
string[] lppPathNames,
int arrayLen,
[MarshalAs(UnmanagedType.Struct)]
out object varArray);

newarr [mscorlib]System.String
stloc.s CS$0$0000
ldloc.s CS$0$0000
ldc.i4.0
ldstr "hoi"
stelem.ref
ldloc.s CS$0$0000

: ldc.i4.1

ldstr "doei"

: stelem.ref

ldloc.s CS$0$0000

: stloc.1

ldloc.1
ldc.i4.2
ldloca.s bla
call int32 NWCNameTranslate::ADsBuildVarArrayStr(string[], int32,
object&)

Reply to this Message

Lucvdv - 18 Nov 2005 09:32 GMT

On Fri, 18 Nov 2005 01:44:14 +0100, "Egbert Nierop $MVP for IIS$"
<egbert_nierop@nospam.invalid> wrote:

> sample what I would like to pass to a win32 function
>
[quoted text clipped - 3 lines]
> string [] elements
> }

Egbert,

I don't know if it is supposed to work in 2.0, but I had the same problem
in VB.Net with CLR 1.1, and there I did get an exception at runtime: "Can
not marshal field xxx of type yyyy: This type can not be marshaled as a
structure field." (xxx is a string array)

see Message-ID: <mheon1l85fask6vtsrq3bnriqrflaj7jne@4ax.com>
(posted yesterday, "Marshal array in structure")

Reply to this Message

Egbert Nierop (MVP for IIS) - 20 Nov 2005 09:59 GMT

> On Fri, 18 Nov 2005 01:44:14 +0100, "Egbert Nierop $MVP for IIS$"
> <egbert_nierop@nospam.invalid> wrote:
[quoted text clipped - 13 lines]
> not marshal field xxx of type yyyy: This type can not be marshaled as a
> structure field." (xxx is a string array)

This might be the only reason to jump to MC++ for separate reasons.

Reply to this Message

jg - 21 Nov 2005 05:41 GMT

take a look at the thread for "passing C# array to and from C array"
try one of them by ptr and by real array. ODN't know if it work for string
at all, depending on the char encoding.
(ansi vs unicode)

>> On Fri, 18 Nov 2005 01:44:14 +0100, "Egbert Nierop $MVP for IIS$"
>> <egbert_nierop@nospam.invalid> wrote:
[quoted text clipped - 15 lines]
>>
> This might be the only reason to jump to MC++ for separate reasons.

Reply to this Message

interop for string[] array

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