Marshalling string to PWSTR

[Roshan]

Hi List,

I am trying to call a method from a native DLL which takes a PWSTR as
an input param. From my managed code (C#), I want to pass a string as a
parameter. How do I convert a C# string to a PWSTR?

Currently I am using

[DllImport("Some .dll", SetLastError = true, CharSet = CharSet.Unicode ,
EntryPoint = "SomeMethod ")]
public static extern bool SomeMethod(IntP tr fileName); //PWSTR

and calling as

string str = "roshan";
bool val = SomeMethod(Mars hal.StringToHGl obalAnsi(str));

My native method has the signature

bool SomeMethod(PWST R fileName)

If I print the received value using printf it works fine, but when I
use it as a parameter to some Win32 APIs it fails. The problem seems to
be that I am converting the string to an ANSI string and not unicode
/wide char (PWSTR) that the native method expects.

Using Marshal.StringT oHGlobalAuto() & Marshal.StringT oHGlobalUni()
don't work.

Any help is greatly appreciated.

Thanks,
Roshan

[Roshan]

Hi Vadym,

I already tried using [MarshalAs(Unman agedType.LPWStr )]. It doesn't
work. In my native DLL if I print the parameter using printf, I get
just the first character.

Regards,
Roshan

Vadym Stetsyak wrote:

Hello, Roshan!

Try

[DllImport("Some .dll", SetLastError = true, CharSet =
CharSet.Unicode ,
EntryPoint = "SomeMethod ")]
public static extern bool SomeMethod(([MarshalAs(LPWSt r)] string fileName);
RI am trying to call a method from a native DLL which takes a PWSTR as
Ran input param. From my managed code (C#), I want to pass a string as
Ra
Rparameter. How do I convert a C# string to a PWSTR?

RCurrently I am using

R[DllImport("Some .dll", SetLastError = true, CharSet =
RCharSet.Unicod e,
REntryPoint = "SomeMethod ")]
R public static extern bool SomeMethod(IntP tr fileName);
R//PWSTR

Rand calling as

Rstring str = "roshan";
Rbool val = SomeMethod(Mars hal.StringToHGl obalAnsi(str));

RMy native method has the signature

R bool SomeMethod(PWST R fileName)

RIf I print the received value using printf it works fine, but when I
Ruse it as a parameter to some Win32 APIs it fails. The problem seems
Rto
Rbe that I am converting the string to an ANSI string and not unicode
R/wide char (PWSTR) that the native method expects.

RUsing Marshal.StringT oHGlobalAuto() & Marshal.StringT oHGlobalUni()
Rdon't work.

RAny help is greatly appreciated.

RThanks,
RRoshan
--
Regards, Vadym Stetsyak
www: http://vadmyst.blogspot.com

[mehr13]

Try declaring the C++ function param as BSTR;

bool SomeMethod(BSTR fileName);

[DllImport("Some .dll", SetLastError = true, CharSet =
CharSet.Unicode ,
EntryPoint = "SomeMethod ")]
public static extern bool SomeMethod(([In,
MarshalAs(Unman agedType.BStr)] string fileName);

MH

Roshan wrote:

Hi Vadym,

I already tried using [MarshalAs(Unman agedType.LPWStr )]. It doesn't
work. In my native DLL if I print the parameter using printf, I get
just the first character.

Regards,
Roshan

Vadym Stetsyak wrote:

Hello, Roshan!

Try

[DllImport("Some .dll", SetLastError = true, CharSet =
CharSet.Unicode ,
EntryPoint = "SomeMethod ")]
public static extern bool SomeMethod(([MarshalAs(LPWSt r)] string fileName);
RI am trying to call a method from a native DLL which takes a PWSTR as
Ran input param. From my managed code (C#), I want to pass a string as
Ra
Rparameter. How do I convert a C# string to a PWSTR?

RCurrently I am using

R[DllImport("Some .dll", SetLastError = true, CharSet =
RCharSet.Unicod e,
REntryPoint = "SomeMethod ")]
R public static extern bool SomeMethod(IntP tr fileName);
R//PWSTR

Rand calling as

Rstring str = "roshan";
Rbool val = SomeMethod(Mars hal.StringToHGl obalAnsi(str));

RMy native method has the signature

R bool SomeMethod(PWST R fileName)

RIf I print the received value using printf it works fine, but when I
Ruse it as a parameter to some Win32 APIs it fails. The problem seems
Rto
Rbe that I am converting the string to an ANSI string and not unicode
R/wide char (PWSTR) that the native method expects.

RUsing Marshal.StringT oHGlobalAuto() & Marshal.StringT oHGlobalUni()
Rdon't work.

RAny help is greatly appreciated.

RThanks,
RRoshan
--
Regards, Vadym Stetsyak
www: http://vadmyst.blogspot.com