C++ CLI System.String^ to MFC LPCTSTR

Question

How would I convert a System (.net) C++\CLI String^ into a MFC C++ LPCTSTR string.

It is very easy to get a LPCTSTR into String^, but so far found nothing on doing it the other way around.

Solution 1

If you have Visual Studio 2008 or above, you should be able to do this using the C++/CLI marshaling library, like so:

#include <msclr\marshal.h>

using namespace System;
using namespace msclr::interop;

...

String^ cliString;
marshal_context context;

LPCTSTR cstr = context.marshal_as<const TCHAR*>(cliString);

More information on marshaling between types on MSDN: Overview of Marshaling in C++

Solution 2

You might want to try Marshal::StringToHGlobalUni, Marshal::StringToHGlobalAuto or Marshal::StringToHGlobalAnsi.

Remember the allocated unmanaged strings will need to be freed with Marshal::FreeHGlobal.

Comments

[TeaWolf]

Why not use LPCTSTR tstr = context.marshal_as< const TCHAR* >( cliString) and let the build environment take care of the actual string type?

[Amy Sutedja]

I've taken you up on your sensible idea, which for some reason had slipped my mind. Thanks!

[Stijn Tallon]

What's the difference between this marshal compared to the marshal in the other answer?

[Amy Sutedja]

Besides better semantics, using marshal_context means that the allocated string is destroyed when the context is destroyed. Calling Marshal::StringToHGlobalAuto, on the other hand, requires you to FreeHGlobal the returned string.