Re: why memory leak here?

From:

"Giovanni Dicanio" <giovanni.dicanio@invalid.it>

Newsgroups:

microsoft.public.vc.language

Date:

Tue, 18 Sep 2007 10:57:14 +0200

Message-ID:

<eEfsWId#HHA.5360@TK2MSFTNGP03.phx.gbl>

"Vivienne" <zhoudan.bupt@gmail.com> ha scritto nel messaggio
news:1190097684.943523.50720@y42g2000hsy.googlegroups.com...

I am using a c# library in my c++ project, so the function that
convert System::String to basic_string is often called. But when
debugging, I get the memory leak report.

here is the function:

void convert(System::String ^ s, std::string& os ){
using namespace Runtime::InteropServices;
pin_ptr<const wchar_t> wch = PtrToStringChars(s);

Hi,

I'm not a C++/CLI expert, however, why don't you use
Marshal::StringToHGlobalAnsi for the conversion?

e.g.

void Convert(
  System::String ^ sIn, // input - managed string
  std::string & sOut // output - unmanaged string
)
{
  // Marshal the managed string to unmanaged memory
  char * stringPtr = (char *) Marshal::StringToHGlobalAnsi(
sIn ).ToPointer();

  // Deep-copy to std::string
  sOut = std::string( stringPtr );

  // Free the temporary unmanaged string memory
  Marshal::FreeHGlobal( IntPtr(stringPtr) );

}

Note that I would very much prefer a conversion to *Unicode* strings, i.e.
use Marshal::StringToHGlobalUni, and use *std::wstring* instead of
std::string.
(I would use std::string just to store UTF-8 Unicode strings. I would really
consider ANSI strings as some form of computer archaeology :-)

Giovanni