Help about error! C++

[G00DGamer]

Hello everyone, I'm new here and I need some help. I'm having error like:

Debug Assertion Failed!

Program: C:\WINDOWS\SYSTEM3MSVCP110D.all
File: C:\Program Files (x86)\Microsoft Visual Studio 11.0\VC\include\xstring

Expression: invalid null pointer

And then suggestions to see C++ documentation...

heres where it drops error:

void StringtoString (String ^ miestasi, string & os)
{
using namespace Runtime::InteropServices;
const char* chars = (const char*) (Marshal::StringToHGlobalAnsi(miestasi)).ToPointer();
os = chars;
Marshal::FreeHGlobal(IntPtr((void*)chars));


}



and here:



private: System::Void button1_Click(System::Object^ sender, System::EventArgs^ e) {



string miestas[20], os;
String ^ miestasi;
int il[20], al[20], val[20], kaina[20], i;

StringtoString(miestasi,os);

fr << os << endl;



}

[z05DSL3A]

String ^ miestasi; doesn't create a string. You would need to do something like String^ string1 = "This is a string created by assignment.";.

[G00DGamer]

I'm making a windows form and I'll type it by myself.

[z05DSL3A]

G00DGamer wrote:

I'm making a windows form

Yes, I can see that.

and wrote:

and I'll type it by myself.

errm okay, should I take it that you didn't understand what I said?

[G00DGamer]

Maybe... So how should it look then???

[z05DSL3A]

Something like this:

#include "stdafx.h"
#include <iostream>
#include <string>

using namespace System;
using namespace System::Runtime::InteropServices;

void StringToString(System::String ^ managed, std::string & native)
{
	char * stringPtr = (char *)Marshal::StringToHGlobalAnsi(managed).ToPointer();

	native = std::string(stringPtr);

	Marshal::FreeHGlobal(IntPtr(stringPtr));
	
}

int main(array<System::String ^> ^args)
{
	System::String^ managedString = "Hello World";
	std::string nativeString;

	StringToString(managedString, nativeString);

	std::cout << nativeString << std::endl;

    return 0;
}

NB:This is for a CLR Console Application Project and is untested

Or

#include "stdafx.h"
#include <iostream>
#include <string>
#include <msclr\marshal_cppstd.h>

using namespace System;
using namespace msclr::interop;


void StringToString(System::String ^ managed, std::string & native)
{
	msclr::interop::marshal_context context;
	native = context.marshal_as<std::string>(managed);
}

int main(array<System::String ^> ^args)
{
	System::String^ managedString = "Hello World";
	std::string nativeString;

	StringToString(managedString, nativeString);

	std::cout << nativeString << std::endl;

    return 0;
}