Hi Olivier,

Based on my understanding, your scenario is:
1) You're writing a wrapper in managed C++ to wrap some unmanaged code
2) The input is a StringBuilder, the outout is also a StringBuilder
3) You don't want to use DllImport to do the marshaling of StringBuilder

Please correct me if I've misunderstood anything.

I believe you could use PtrToStringChars() to access the internal wchar_t*
of a managed string. For the reverse part, you could use
Marshal::PtrToStringAnsi or Uni to convert from ANSI or Unicode to a
managed string.

#StringConvertor : A convertor class for managed-unmanaged string
conversions that handles memory de-allocations - The Code Project - Managed
C++
http://www.codeproject.com/managedcpp/StringConvertor.asp
A convertor class for managed-unmanaged string conversions that handles
memory de-allocations. Caller need not worry about freeing unmanaged memory
allocations.

#I Love that New Syntax Smell : Pointer to String chars - Everett style
http://blogs.msdn.com/arich/archive/2003/12/22/45219.aspx
Can I get a native pointer to the data in a CLR String?  The short answer
is yes, so long as you don't mind a wchar_t* - which is native analog of
the actual backing store type for a CLR String (the CLR type System::Char).

#I Love that New Syntax Smell : Pinning Pointers
http://blogs.msdn.com/arich/archive/2004/08/27/221588.aspx
Pinning Pointers

#Managed C++ - Learn by Example - Part 1 - The Code Project - Managed C++
http://www.codeproject.com/managedcpp/cpptomancpp.asp
VC++ provides a helper function, PtrToStringChars(), defined in "vcclr.h"
that allows you to access the internal wchar_t* of a managed string.

Sincerely,
Walter Wang (wawang@online.microsoft.com, remove 'online.')
Microsoft Online Community Support

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