problem in using win32 DLL in c#

[Ryanivanka]

hi ,everyone ,please check my codes,i am really confused.

the codes of win32 dll is as follows:
*************** ********the win32 DLL writen in c++************ *****
extern "C"
{
__declspec(dlle xport) WCHAR* __stdcall getWNameOfCompo nnet();

}

WCHAR name[100];

BOOL APIENTRY DllMain( HMODULE hModule,
DWORD ul_reason_for_c all,
LPVOID lpReserved
)
{
return TRUE;
}
WCHAR* getWNameOfCompo nnet(){
return name;
}

*************** *************** *************** ***
*************** ******the win32 .def file*********** *

EXPORT
getWNameOfCompo nnet @1
*************** *************** *************** ********
and I try to use the export in c#,but I can not get anything from
getprocaddress( ,.)

**************i mport the prototype of api**
[DllImport ("kernel32.dll" ,EntryPoint="Lo adLibraryW",
CharSet=CharSet .Unicode,Callin gConvention=Cal lingConvention. StdCall,
SetLastError =true)]
public extern static IntPtr LoadLibrary(Str ing lpFileName);

[DllImport("Kern el32", EntryPoint = "GetProcAddress ",
CharSet=CharSet .Unicode ,CallingConvent ion =
CallingConventi on.StdCall,
SetLastError = true)]
public extern static IntPtr GetProcAddress(
IntPtr handle,
[MarshalAs(Unman agedType.LPWStr )]string funcname);

*************** *******
**************g et the export from my dll***
public delegate string getwname();

private static Delegate GetAddress(IntP tr dllModule, string
functionname, Type t)
{

IntPtr addr = GetProcAddress( dllModule, functionname);
//addr is always zero.why?

if (addr == IntPtr.Zero )
return null;
else
return Marshal.GetDele gateForFunction Pointer(addr, t);
}

public String callGetWname()
{
IntPtr huser32 =IntPtr.Zero ;
huser32 = LoadLibrary("my .dll");//the huser32 is ok,the
dll is loaded.
getwname mygetw = (getwname)GetAd dress(huser32,
"getWNameOfComp onnet",
typeof(getwname ));

}

*************** *************** **
the getProcAddress( ..) doesn't work.Where am i wrong?

[Ben Voigt [C++ MVP]]

the getProcAddress( ..) doesn't work.Where am i wrong?

Does the filename of the DLL you need to load change after compile time? If
not, let p/invoke handle all the dynamic loading mess for you and just use
DllImport and declare the function you need to call.

[Ryanivanka]

hi,Ben

the export of the DLL is right. I check them with a tool software.
and I change the prototype of getProcAddress( ..) in C# as follows:
*************** ***********
[DllImport("Kern el32.dll", EntryPoint = "GetProcAddress ", CharSet =
CharSet.Ansi, CallingConventi on = CallingConventi on.StdCall , SetLastError =
true)]
public extern static IntPtr GetProcAddress(
IntPtr handle,
[MarshalAs(Unman agedType.LPStr)]string funcname);
*************** ************

if I change it into unicode ,everything go wrong. I don't why ,maybe
GetProcAddress( ) only has ANSI version.

just put result here for someone may encounter the same problem.

"Ben Voigt [C++ MVP]" <rb*@nospam.nos pamдÈëÏûÏ¢ÐÂÎÅ :eC************ **@TK2MSFTNGP06 .phx.gbl...

>the getProcAddress( ..) doesn't work.Where am i wrong?

Does the filename of the DLL you need to load change after compile time?
If not, let p/invoke handle all the dynamic loading mess for you and just
use DllImport and declare the function you need to call.

[Jeff Winn]

**************i mport the prototype of api**

[DllImport ("kernel32.dll" ,EntryPoint="Lo adLibraryW",
CharSet=CharSet .Unicode,Callin gConvention=Cal lingConvention. StdCall,
SetLastError =true)]
public extern static IntPtr LoadLibrary(Str ing lpFileName);

Just FYI, you shouldn't specify the LoadLibraryW entry point unless you
specified ExactSpelling = true on the DllImport attribute. You're already
specifying to use the Unicode character set, as such that would be handled
automatically. Also, you don't need to specify the EntryPoint unless it's
different than the name of the function you're defining. Just some nice
things you might want to do to help simplify your code. :o)

For example: This would need it.
[DllImport("myfi le.dll", EntryPoint = "Foo")]
public static extern void Bar();

After looking in both the WinBase.h and Windows.h header files the MSDN
documentation states they're located in there was only a single declaration
for the GetProcAddress function - which leads me to believe you are correct
when you said that only the ANSI version is available. Not to mention there
is no information in the MSDN documentation indicating there is both a
Unicode and ANSI version available.

Perhaps because old C didn't allow Unicode characters in their definitions.
I don't know, I'm completely guessing there. Never used it before so I
couldn't say either way for sure. That's the only reason I could think of
why there wouldn't be a unicode version of the definition.

"Ryanivanka " <sa********@gma il.comwrote in message
news:%2******** ********@TK2MSF TNGP03.phx.gbl. ..

hi,Ben

the export of the DLL is right. I check them with a tool software.
and I change the prototype of getProcAddress( ..) in C# as follows:
*************** ***********
[DllImport("Kern el32.dll", EntryPoint = "GetProcAddress ", CharSet =
CharSet.Ansi, CallingConventi on = CallingConventi on.StdCall , SetLastError
= true)]
public extern static IntPtr GetProcAddress(
IntPtr handle,
[MarshalAs(Unman agedType.LPStr)]string funcname);
*************** ************

if I change it into unicode ,everything go wrong. I don't why ,maybe
GetProcAddress( ) only has ANSI version.

just put result here for someone may encounter the same problem.

"Ben Voigt [C++ MVP]" <rb*@nospam.nos pam>
дÈëÏûÏ¢ÐÂÎÅ:eC **************@ TK2MSFTNGP06.ph x.gbl...

>>the getProcAddress( ..) doesn't work.Where am i wrong?

Does the filename of the DLL you need to load change after compile time?
If not, let p/invoke handle all the dynamic loading mess for you and just
use DllImport and declare the function you need to call.

[Pavel Minaev]

On Jul 8, 6:34*pm, Ryanivanka <sarah.h...@gma il.comwrote:

the getProcAddress( ..) doesn't work.Where am i wrong?

Here:

[DllImport("Kern el32", EntryPoint = "GetProcAddress ",
CharSet=CharSet .Unicode ,CallingConvent ion =
CallingConventi on.StdCall,
SetLastError = true)]

You either need to use CharSet=CharSet .Auto, or
EntryPoint="Get ProcAddressW". If you specify CharSet explicitly, P/
Invoke won't auto-decorate the function name.

[Ben Voigt [C++ MVP]]

Ryanivanka wrote:

hi,Ben

the export of the DLL is right. I check them with a tool software.

Why are you using GetProcAddress? Use a DllImport attribute on *your*
function setting EntryPoint correctly and p/invoke will call LoadLibrary and
GetProcAddress for you.

>

and I change the prototype of getProcAddress( ..) in C# as follows:
*************** ***********
[DllImport("Kern el32.dll", EntryPoint = "GetProcAddress ",
CharSet = CharSet.Ansi, CallingConventi on = CallingConventi on.StdCall ,
SetLastError = true)]
public extern static IntPtr GetProcAddress(
IntPtr handle,
[MarshalAs(Unman agedType.LPStr)]string funcname);
*************** ************

if I change it into unicode ,everything go wrong. I don't why ,maybe
GetProcAddress( ) only has ANSI version.

just put result here for someone may encounter the same problem.

"Ben Voigt [C++ MVP]" <rb*@nospam.nos pam>
дÈëÏûÏ¢ÐÂÎÅ:eC **************@ TK2MSFTNGP06.ph x.gbl...

>>the getProcAddress( ..) doesn't work.Where am i wrong?

Does the filename of the DLL you need to load change after compile
time? If not, let p/invoke handle all the dynamic loading mess for
you and just use DllImport and declare the function you need to call.

[Ryanivanka]

Thank you, Pavel.
It does work if I kick out the"CharSet" attribute.
-----------------------------------------
ÔÚ Wed, 9 Jul 2008 07:20:02 -0700 (PDT) £¬Pavel MinaevдµÀ£º

>On Jul 8, 6:34*pm, Ryanivanka <sarah.h...@gma il.comwrote:

>the getProcAddress( ..) doesn't work.Where am i wrong?

Here:

>[DllImport("Kern el32", EntryPoint = "GetProcAddress ",
CharSet=CharSe t.Unicode ,CallingConvent ion =
CallingConvent ion.StdCall,
SetLastError = true)]

You either need to use CharSet=CharSet .Auto, or
EntryPoint="Ge tProcAddressW". If you specify CharSet explicitly, P/
Invoke won't auto-decorate the function name.

-----------------------------------------

Ö Àñ£¡
Ryanivanka
sa********@gmai l.com

[Ryanivanka]

hi,Ben.
what you ask remind me of another question.

I was told if I use LoadLibrary(..) to load a DLL, I have to freeLibrary(..) by myself too,because CLR won't do that for me? is this correct?

I use LoadLibrary(..) to control the bind of DLL by myself.And if I import my function using EntryPoint,woul d the DLL stay in the process's virtual address space until the process is ended?

-----------------------------------------
ÔÚ Wed, 9 Jul 2008 11:21:38 -0500 £¬Ben Voigt [C++ MVP]дµÀ£º

>Ryanivanka wrote:

>hi,Ben

the export of the DLL is right. I check them with a tool software.

Why are you using GetProcAddress? Use a DllImport attribute on *your*
function setting EntryPoint correctly and p/invoke will call LoadLibrary and
GetProcAddre ss for you.

>>

and I change the prototype of getProcAddress( ..) in C# as follows:
************** ************
[DllImport("Kern el32.dll", EntryPoint = "GetProcAddress ",
CharSet = CharSet.Ansi, CallingConventi on = CallingConventi on.StdCall ,
SetLastError = true)]
public extern static IntPtr GetProcAddress(
IntPtr handle,
[MarshalAs(Unman agedType.LPStr)]string funcname);
************** *************

if I change it into unicode ,everything go wrong. I don't why ,maybe
GetProcAddress () only has ANSI version.

just put result here for someone may encounter the same problem.

"Ben Voigt [C++ MVP]" <rb*@nospam.nos pam>
дÈëÏûÏ¢ÐÂÎÅ:e C************** @TK2MSFTNGP06.p hx.gbl...

>>>the getProcAddress( ..) doesn't work.Where am i wrong?

Does the filename of the DLL you need to load change after compile
time? If not, let p/invoke handle all the dynamic loading mess for
you and just use DllImport and declare the function you need to call.

-----------------------------------------

Ö Àñ£¡
Ryanivanka
sa********@gmai l.com

[Pavel Minaev]

On Jul 10, 4:39*am, Ryanivanka <sarah.h...@gma il.comwrote:

I was told if I use LoadLibrary(..) to load a DLL, I have to freeLibrary(... ) by myself too,because CLR won't do that for me? is this correct?

Yes. CLR garbage collector only collects memory, everything else is
"unmanaged resources", and you have to take care of it yourself.

I use LoadLibrary(..) to control the bind of DLL by myself.And if I import my function using EntryPoint,woul d the DLL stay in the process's virtual address space until the process is ended?

Yes.