Hi,

I need to acces a string (wchar_t*) in a C++ (win32) DLL from within
the Compact Framework.
The C++ Syntax is like this:

extern "C" __declspec(dllexport) int SomeFunc(wchar_t
*someString[128])
{
	*someString = _T("Enter some text...");
}

In the c# code I declare the function as

[DllImport("myTest.dll", EntryPoint = "SomeFunc")]
static extern int SomeFunc(StringBuilder someString);

and access it with

StringBuilder sb = new StringBuilder(128);
int result = SomeFunc(sb);

The only thing I get back are 2 hieroglyphs.
I tried passing in a string and a IntPtr as well, but nothing works.

The netcf-interop-logfile looks like this:

int  SomeFunc(System.Text.StringBuilder);
int (I4_VAL) SomeFunc(WCHAR * (STRINGBUILDER_LPWSTR));

Can anyone give me a hint what I am doing wrong?

Thanks in advance.

Mike

Hi Mike,

Use LPTSTR instead of wchar_t *

--
Regards,
Christian Resma Helle
http://christian-helle.blogspot.com

On Jul 13, 12:25 pm, Mike  wrote:

> Hi,
>
> I need to acces a string (wchar_t*) in a C++ (win32) DLL from within
> the Compact Framework.
> The C++ Syntax is like this:
>
> extern "C" __declspec(dllexport) int SomeFunc(wchar_t
> *someString[128])
> {
>         *someString = _T("Enter some text...");
>
> }
>
> In the c# code I declare the function as
>
> [DllImport("myTest.dll", EntryPoint = "SomeFunc")]
> static extern int SomeFunc(StringBuilder someString);
>
> and access it with
>
> StringBuilder sb = new StringBuilder(128);
> int result = SomeFunc(sb);
>
> The only thing I get back are 2 hieroglyphs.
> I tried passing in a string and a IntPtr as well, but nothing works.
>
> The netcf-interop-logfile looks like this:
>
> int  SomeFunc(System.Text.StringBuilder);
> int (I4_VAL) SomeFunc(WCHAR * (STRINGBUILDER_LPWSTR));
>
> Can anyone give me a hint what I am doing wrong?
>
> Thanks in advance.
>
> Mike

Hi Mike,

Here's an example of how I would normally do it:


[C++ CODE]

extern "C" __declspec(dllexport) int TTN_GetApplicationVersion(
  int* iError, LPTSTR szVersion, int *iBuildNumber )
{
  MTomTomCommunicationLayerInterface *comms =
    DEFAULT_TRANSPORTATION_LAYER(CLIENT_NAME,2005,TOMTOM_TCPIP_PORT);

  CTomTomAPI api(*comms);
  CTomTomAPI::TVersion version;
  res = api.GetApplicationVersion(&err, &version);
  *iError = err.iError;

  TCHAR str[16];
  _stprintf(str, TEXT("%S"), version.iVersion);
  lstrcpy( szVersion, (LPTSTR)str );
  *iBuildNumber = version.iBuildNumber;

  delete comms;
  return res;
}

[C# CODE]

[DllImport("TTSDK.dll", EntryPoint="TTN_GetApplicationVersion")]
static extern int TTN_GetApplicationVersion(
  ref int iError, StringBuilder szVersion, ref int iBuildNumber);

public void TestGetApplicationVersion()
{
  StringBuilder szVersion = new StringBuilder();
  int iBuildNumber = 0;

  TTN_GetApplicationVersion(ref iError, szVersion, ref iBuildNumber);
}


The code above is a wrapper to a C++ SDK to expose C style methods. Hope 
this helps you.

-- 
Regards,
Christian Resma Helle
http://christian-helle.blogspot.com


"Mike"  wrote in message 
news:1184322329.190038.310670@n2g2000hse.googlegroups.com...

> Hi,
>
> I need to acces a string (wchar_t*) in a C++ (win32) DLL from within
> the Compact Framework.
> The C++ Syntax is like this:
>
> extern "C" __declspec(dllexport) int SomeFunc(wchar_t
> *someString[128])
> {
> *someString = _T("Enter some text...");
> }
>
> In the c# code I declare the function as
>
> [DllImport("myTest.dll", EntryPoint = "SomeFunc")]
> static extern int SomeFunc(StringBuilder someString);
>
> and access it with
>
> StringBuilder sb = new StringBuilder(128);
> int result = SomeFunc(sb);
>
> The only thing I get back are 2 hieroglyphs.
> I tried passing in a string and a IntPtr as well, but nothing works.
>
> The netcf-interop-logfile looks like this:
>
> int  SomeFunc(System.Text.StringBuilder);
> int (I4_VAL) SomeFunc(WCHAR * (STRINGBUILDER_LPWSTR));
>
> Can anyone give me a hint what I am doing wrong?
>
> Thanks in advance.
>
> Mike
> 

On 13 Jul., 12:59, Christian Resma Helle  wrote:

> Hi Mike,
>
> Use LPTSTR instead of wchar_t *
>
> --
> Regards,
> Christian Resma Hellehttp://christian-helle.blogspot.com
>
> On Jul 13, 12:25 pm, Mike  wrote:
>
>
>
> > Hi,
>
> > I need to acces a string (wchar_t*) in a C++ (win32) DLL from within
> > the Compact Framework.
> > The C++ Syntax is like this:
>
> > extern "C" __declspec(dllexport) int SomeFunc(wchar_t
> > *someString[128])
> > {
> >         *someString = _T("Enter some text...");
>
> > }
>
> > In the c# code I declare the function as
>
> > [DllImport("myTest.dll", EntryPoint = "SomeFunc")]
> > static extern int SomeFunc(StringBuilder someString);
>
> > and access it with
>
> > StringBuilder sb = new StringBuilder(128);
> > int result = SomeFunc(sb);
>
> > The only thing I get back are 2 hieroglyphs.
> > I tried passing in a string and a IntPtr as well, but nothing works.
>
> > The netcf-interop-logfile looks like this:
>
> > int  SomeFunc(System.Text.StringBuilder);
> > int (I4_VAL) SomeFunc(WCHAR * (STRINGBUILDER_LPWSTR));
>
> > Can anyone give me a hint what I am doing wrong?
>
> > Thanks in advance.
>
> > Mike- Zitierten Text ausblenden -
>
> - Zitierten Text anzeigen -


Hi Christian,

thanks for the response. I tried it, but I get a similar result. There
is only returnd 00000000h: 3F 79

Hi Mike,

How does your native method look like?

--
Regards,
Christian Resma Helle
http://christian-helle.blogspot.com


On Jul 13, 1:16 pm, Mike  wrote:

> On 13 Jul., 12:59, Christian Resma Helle  wrote:
>
>
>
>
>
> > Hi Mike,
>
> > Use LPTSTR instead of wchar_t *
>
> > --
> > Regards,
> > Christian Resma Hellehttp://christian-helle.blogspot.com
>
> > On Jul 13, 12:25 pm, Mike  wrote:
>
> > > Hi,
>
> > > I need to acces a string (wchar_t*) in a C++ (win32) DLL from within
> > > the Compact Framework.
> > > The C++ Syntax is like this:
>
> > > extern "C" __declspec(dllexport) int SomeFunc(wchar_t
> > > *someString[128])
> > > {
> > >         *someString = _T("Enter some text...");
>
> > > }
>
> > > In the c# code I declare the function as
>
> > > [DllImport("myTest.dll", EntryPoint = "SomeFunc")]
> > > static extern int SomeFunc(StringBuilder someString);
>
> > > and access it with
>
> > > StringBuilder sb = new StringBuilder(128);
> > > int result = SomeFunc(sb);
>
> > > The only thing I get back are 2 hieroglyphs.
> > > I tried passing in a string and a IntPtr as well, but nothing works.
>
> > > The netcf-interop-logfile looks like this:
>
> > > int  SomeFunc(System.Text.StringBuilder);
> > > int (I4_VAL) SomeFunc(WCHAR * (STRINGBUILDER_LPWSTR));
>
> > > Can anyone give me a hint what I am doing wrong?
>
> > > Thanks in advance.
>
> > > Mike- Zitierten Text ausblenden -
>
> > - Zitierten Text anzeigen -
>
> Hi Christian,
>
> thanks for the response. I tried it, but I get a similar result. There
> is only returnd 00000000h: 3F 79- Hide quoted text -
>
> - Show quoted text -

On 13 Jul., 13:22, Christian Resma Helle  wrote:

> Hi Mike,
>
> How does your native method look like?
>
> --
> Regards,
> Christian Resma Hellehttp://christian-helle.blogspot.com
>
> On Jul 13, 1:16 pm, Mike  wrote:
>
>
>
> > On 13 Jul., 12:59, Christian Resma Helle  wrote:
>
> > > Hi Mike,
>
> > > Use LPTSTR instead of wchar_t *
>
> > > --
> > > Regards,
> > > Christian Resma Hellehttp://christian-helle.blogspot.com
>
> > > On Jul 13, 12:25 pm, Mike  wrote:
>
> > > > Hi,
>
> > > > I need to acces a string (wchar_t*) in a C++ (win32) DLL from within
> > > > the Compact Framework.
> > > > The C++ Syntax is like this:
>
> > > > extern "C" __declspec(dllexport) int SomeFunc(wchar_t
> > > > *someString[128])
> > > > {
> > > >         *someString = _T("Enter some text...");
>
> > > > }
>
> > > > In the c# code I declare the function as
>
> > > > [DllImport("myTest.dll", EntryPoint = "SomeFunc")]
> > > > static extern int SomeFunc(StringBuilder someString);
>
> > > > and access it with
>
> > > > StringBuilder sb = new StringBuilder(128);
> > > > int result = SomeFunc(sb);
>
> > > > The only thing I get back are 2 hieroglyphs.
> > > > I tried passing in a string and a IntPtr as well, but nothing works.
>
> > > > The netcf-interop-logfile looks like this:
>
> > > > int  SomeFunc(System.Text.StringBuilder);
> > > > int (I4_VAL) SomeFunc(WCHAR * (STRINGBUILDER_LPWSTR));
>
> > > > Can anyone give me a hint what I am doing wrong?
>
> > > > Thanks in advance.
>
> > > > Mike- Zitierten Text ausblenden -
>
> > > - Zitierten Text anzeigen -
>
> > Hi Christian,
>
> > thanks for the response. I tried it, but I get a similar result. There
> > is only returnd 00000000h: 3F 79- Hide quoted text -
>
> > - Show quoted text -- Zitierten Text ausblenden -
>
> - Zitierten Text anzeigen -


Hi Christian,

I noticed in your example that you do not use the braces after the
LPSTR keyword. But if I remove them in my method I get a compile
error
C2440: '=' : cannot convert from 'const wchar_t [23]' to 'WCHAR' in
the line

*someString = _T("Enter some text...");

Your example helps me very much, because I'm also dealing with a
native sdk. But I also need to make Debug Output directly in my code.

I also noticed, that you do not initialize your StringBuilder with the
capazity:
StringBuilder szVersion = new StringBuilder();

Is that correct?

Thanl you very much.

Mike

Mike,
Your C++ API method uses an array of wide character strings.  
This method would work if you declared your C++ method as

extern "C" __declspec(dllexport) int SomeFunction(LPSTR someString
{
    wsprintf(someString, _T("Enter some text...");
}

Then you should be able to

"Mike" wrote:


> Hi,
> 
> I need to acces a string (wchar_t*) in a C++ (win32) DLL from within
> the Compact Framework.
> The C++ Syntax is like this:
> 
> extern "C" __declspec(dllexport) int SomeFunc(wchar_t
> *someString[128])
> {
> 	*someString = _T("Enter some text...");
> }
> 
> In the c# code I declare the function as
> 
> [DllImport("myTest.dll", EntryPoint = "SomeFunc")]
> static extern int SomeFunc(StringBuilder someString);
> 
> and access it with
> 
> StringBuilder sb = new StringBuilder(128);
> int result = SomeFunc(sb);
> 
> The only thing I get back are 2 hieroglyphs.
> I tried passing in a string and a IntPtr as well, but nothing works.
> 
> The netcf-interop-logfile looks like this:
> 
> int  SomeFunc(System.Text.StringBuilder);
> int (I4_VAL) SomeFunc(WCHAR * (STRINGBUILDER_LPWSTR));
> 
> Can anyone give me a hint what I am doing wrong?
> 
> Thanks in advance.
> 
> Mike
> 
> 

On 13 Jul., 15:04, dbgrick  wrote:

> Mike,
> Your C++ API method uses an array of wide character strings.  
> This method would work if you declared your C++ method as
>
> extern "C" __declspec(dllexport) int SomeFunction(LPSTR someString
> {
>     wsprintf(someString, _T("Enter some text...");
>
> }
>
> Then you should be able to
>
>
>
> "Mike" wrote:
> > Hi,
>
> > I need to acces a string (wchar_t*) in a C++ (win32) DLL from within
> > the Compact Framework.
> > The C++ Syntax is like this:
>
> > extern "C" __declspec(dllexport) int SomeFunc(wchar_t
> > *someString[128])
> > {
> >    *someString = _T("Enter some text...");
> > }
>
> > In the c# code I declare the function as
>
> > [DllImport("myTest.dll", EntryPoint = "SomeFunc")]
> > static extern int SomeFunc(StringBuilder someString);
>
> > and access it with
>
> > StringBuilder sb = new StringBuilder(128);
> > int result = SomeFunc(sb);
>
> > The only thing I get back are 2 hieroglyphs.
> > I tried passing in a string and a IntPtr as well, but nothing works.
>
> > The netcf-interop-logfile looks like this:
>
> > int  SomeFunc(System.Text.StringBuilder);
> > int (I4_VAL) SomeFunc(WCHAR * (STRINGBUILDER_LPWSTR));
>
> > Can anyone give me a hint what I am doing wrong?
>
> > Thanks in advance.
>
> > Mike- Zitierten Text ausblenden -
>
> - Zitierten Text anzeigen -


It works! Thank you guys. You really made my day. I was working on
this for 2 days.

Mike

Anytime Mike!

I wrote a small article related to this topic before.

If you're interested, then here's a link to it:
http://christian-helle.blogspot.com/2007/06/integrating-with-tomtom-navigator.html

--
Regards,
Christian Resma Helle
http://christian-helle.blogspot.com


On Jul 13, 3:22 pm, Mike  wrote:

> On 13 Jul., 15:04, dbgrick  wrote:
>
>
>
>
>
> > Mike,
> > Your C++ API method uses an array of wide character strings.  
> > This method would work if you declared your C++ method as
>
> > extern "C" __declspec(dllexport) int SomeFunction(LPSTR someString
> > {
> >     wsprintf(someString, _T("Enter some text...");
>
> > }
>
> > Then you should be able to
>
> > "Mike" wrote:
> > > Hi,
>
> > > I need to acces a string (wchar_t*) in a C++ (win32) DLL from within
> > > the Compact Framework.
> > > The C++ Syntax is like this:
>
> > > extern "C" __declspec(dllexport) int SomeFunc(wchar_t
> > > *someString[128])
> > > {
> > >    *someString = _T("Enter some text...");
> > > }
>
> > > In the c# code I declare the function as
>
> > > [DllImport("myTest.dll", EntryPoint = "SomeFunc")]
> > > static extern int SomeFunc(StringBuilder someString);
>
> > > and access it with
>
> > > StringBuilder sb = new StringBuilder(128);
> > > int result = SomeFunc(sb);
>
> > > The only thing I get back are 2 hieroglyphs.
> > > I tried passing in a string and a IntPtr as well, but nothing works.
>
> > > The netcf-interop-logfile looks like this:
>
> > > int  SomeFunc(System.Text.StringBuilder);
> > > int (I4_VAL) SomeFunc(WCHAR * (STRINGBUILDER_LPWSTR));
>
> > > Can anyone give me a hint what I am doing wrong?
>
> > > Thanks in advance.
>
> > > Mike- Zitierten Text ausblenden -
>
> > - Zitierten Text anzeigen -
>
> It works! Thank you guys. You really made my day. I was working on
> this for 2 days.
>
> Mike- Hide quoted text -
>
> - Show quoted text -

On 13 Jul., 15:34, Christian Resma Helle  wrote:

> Anytime Mike!
>
> I wrote a small article related to this topic before.
>
> If you're interested, then here's a link to it:http://christian-helle.blogspot.com/2007/06/integrating-with-tomtom-n...
>
> --
> Regards,
> Christian Resma Hellehttp://christian-helle.blogspot.com
>
> On Jul 13, 3:22 pm, Mike  wrote:
>
>
>
> > On 13 Jul., 15:04, dbgrick  wrote:
>
> > > Mike,
> > > Your C++ API method uses an array of wide character strings.  
> > > This method would work if you declared your C++ method as
>
> > > extern "C" __declspec(dllexport) int SomeFunction(LPSTR someString
> > > {
> > >     wsprintf(someString, _T("Enter some text...");
>
> > > }
>
> > > Then you should be able to
>
> > > "Mike" wrote:
> > > > Hi,
>
> > > > I need to acces a string (wchar_t*) in a C++ (win32) DLL from within
> > > > the Compact Framework.
> > > > The C++ Syntax is like this:
>
> > > > extern "C" __declspec(dllexport) int SomeFunc(wchar_t
> > > > *someString[128])
> > > > {
> > > >    *someString = _T("Enter some text...");
> > > > }
>
> > > > In the c# code I declare the function as
>
> > > > [DllImport("myTest.dll", EntryPoint = "SomeFunc")]
> > > > static extern int SomeFunc(StringBuilder someString);
>
> > > > and access it with
>
> > > > StringBuilder sb = new StringBuilder(128);
> > > > int result = SomeFunc(sb);
>
> > > > The only thing I get back are 2 hieroglyphs.
> > > > I tried passing in a string and a IntPtr as well, but nothing works.
>
> > > > The netcf-interop-logfile looks like this:
>
> > > > int  SomeFunc(System.Text.StringBuilder);
> > > > int (I4_VAL) SomeFunc(WCHAR * (STRINGBUILDER_LPWSTR));
>
> > > > Can anyone give me a hint what I am doing wrong?
>
> > > > Thanks in advance.
>
> > > > Mike- Zitierten Text ausblenden -
>
> > > - Zitierten Text anzeigen -
>
> > It works! Thank you guys. You really made my day. I was working on
> > this for 2 days.
>
> > Mike- Hide quoted text -
>
> > - Show quoted text -- Zitierten Text ausblenden -
>
> - Zitierten Text anzeigen -


Looks like a great article. I will have a depper look the next week.
The strings in C/C++ always kill me. I'm so glad we don't have to deal
with them like this in the dotnet framework.

Mike

Why?  that's the same thing.


-- 

Chris Tacke, Embedded MVP
OpenNETCF Consulting
Managed Code in an Embedded World
www.OpenNETCF.com


"Christian Resma Helle"  wrote in message 
news:1184324353.261271.123860@q75g2000hsh.googlegroups.com...

> Hi Mike,
>
> Use LPTSTR instead of wchar_t *
>
> --
> Regards,
> Christian Resma Helle
> http://christian-helle.blogspot.com
>
> On Jul 13, 12:25 pm, Mike  wrote:
>> Hi,
>>
>> I need to acces a string (wchar_t*) in a C++ (win32) DLL from within
>> the Compact Framework.
>> The C++ Syntax is like this:
>>
>> extern "C" __declspec(dllexport) int SomeFunc(wchar_t
>> *someString[128])
>> {
>>         *someString = _T("Enter some text...");
>>
>> }
>>
>> In the c# code I declare the function as
>>
>> [DllImport("myTest.dll", EntryPoint = "SomeFunc")]
>> static extern int SomeFunc(StringBuilder someString);
>>
>> and access it with
>>
>> StringBuilder sb = new StringBuilder(128);
>> int result = SomeFunc(sb);
>>
>> The only thing I get back are 2 hieroglyphs.
>> I tried passing in a string and a IntPtr as well, but nothing works.
>>
>> The netcf-interop-logfile looks like this:
>>
>> int  SomeFunc(System.Text.StringBuilder);
>> int (I4_VAL) SomeFunc(WCHAR * (STRINGBUILDER_LPWSTR));
>>
>> Can anyone give me a hint what I am doing wrong?
>>
>> Thanks in advance.
>>
>> Mike
>
>