how to use #pragma data_seq

[ernst20020530]

I should write a Windows32 form, in which I can input Unicode. When I create multiple instances of application.all the form must display some content, and When I change the content, the content in all instances must change according to the changed Unicode.
Now I can get the content of input, but how can I put the value into the variable in commen memory area?

#include "stdafx.h"
#include "windows.h"
#include <memory.h>
#include <TCHAR.h>
//#pragma once

#pragma data_seq("Shared")
volatile wchar_t* content;
#pragma data_seq()
#pragma comment(linker, "/Section:Shared,RWS")


namespace ShareMemory2 {

using namespace System;
using namespace System::ComponentModel;
using namespace System::Collections;
using namespace System::Windows::Forms;
using namespace System:ata;
using namespace System:rawing;

/// <summary>
/// Summary for Form1
///
/// WARNING: If you change the name of this class, you will need to change the
/// 'Resource File Name' property for the managed resource compiler tool
/// associated with all .resx files this class depends on. Otherwise,
/// the designers will not be able to interact properly with localized
/// resources associated with this form.
/// </summary>
public ref class Form1 : public System::Windows::Forms::Form
{
public:
Form1(void)
{
InitializeComponent();
//
//TODO: Add the constructor code here
//
}

protected:
/// <summary>
/// Clean up any resources being used.
/// </summary>
~Form1()
{
if (components)
{
delete components;
}
}
private: System::Windows::Forms::TextBox^ textBox1;
private: System::Windows::Forms::Button^ button1;
protected:

private:
/// <summary>
/// Required designer variable.
/// </summary>
System::ComponentModel::Container ^components;

#pragma region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
void InitializeComponent(void)
{
this->textBox1 = (gcnew System::Windows::Forms::TextBox());
this->button1 = (gcnew System::Windows::Forms::Button());
this->SuspendLayout();
//
// textBox1
//
this->textBox1->Location = System:rawing::Point(67, 26);
this->textBox1->Name = L"textBox1";
this->textBox1->Size = System:rawing::Size(164, 20);
this->textBox1->TabIndex = 0;
//
// button1
//
this->button1->Location = System:rawing::Point(105, 64);
this->button1->Name = L"button1";
this->button1->Size = System:rawing::Size(75, 23);
this->button1->TabIndex = 1;
this->button1->Text = L"button1";
this->button1->UseVisualStyleBackColor = true;
this->button1->Click += gcnew System::EventHandler(this, &Form1::button1_Click);
//
// Form1
//
this->AutoScaleDimensions = System:rawing::SizeF(6, 13);
this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;
this->ClientSize = System:rawing::Size(296, 111);
this->Controls->Add(this->button1);
this->Controls->Add(this->textBox1);
this->Name = L"Form1";
this->Text = L"Form1";
this->Load += gcnew System::EventHandler(this, &Form1::Form1_Load);
this->ResumeLayout(false);
this->PerformLayout();

}
#pragma endregion

private : System::String^ Pwchar_tToString(wchar_t* content){
System::IntPtr ptr(content);
System::String^ string = System::Runtime::InteropServices::Marshal::PtrToStringUni(ptr);
return string;
};

private : wchar_t *StringToPwchar_t(System::String^ str){
IntPtr ptr = System::Runtime::InteropServices::Marshal::StringToHGlobalUni(str);
wchar_t *string = reinterpret_cast<wchar_t*>(ptr.ToPointer());
return string;
};

private: System::Void Form1_Load(System::Object^ sender, System::EventArgs^ e) {
/*wchar_t**/ content=TEXT("abc");
//memcpy((void*)content,content2,4);
wchar_t* cont2=TEXT("abc");
int i=0;
this->textBox1->Text=Pwchar_tToString(cont2);
}

private: System::Void button1_Click(System::Object^ sender, System::EventArgs^ e) {
wchar_t* in=StringToPwchar_t(this->textBox1->Text);
int i=0;
}
};


}

[ahoodin]

#! Use of share memory is really best done with a dll I find:
#2 Load the DLL into every app that will be using the shared memory.
#3 Make functions or classes to access that memory.

Here is an example that shows the ins and outs without getting into too much needless detail:
in your header:

#ifdef _USRDLL
	#define LINKDLL __declspec (dllexport) 
#else
	#define LINKDLL __declspec (dllimport)
#endif

LINKDLL void SetValue(int newvalue);
LINKDLL int GetValue();

then in your cpp:

#pragma data_seg (".myseg")
 intMyShareInt= 0; 
#pragma data_seg()

void SetValue(int newvalue)
{
  MyShareInt=newvalue;
};

int GetValue()
{
  return MyShareInt;
};

#4 You then must specify the correct sharing attributes in the dll for this new named data section in your .def file or with the linker option

/SECTION:.MYSEC,RWS.

#5 You will want to add necessary synchronization such as mutex and semaphore to use these functions in multiple processes and threads.

#6 Please use code tags when posting any amount of code. Highlight your code and click the white code button on the right of the editor.(thanks)

HTH,

[rxbagain]

And share not only the pointer but also the data it is pointing to

In your code, the "wchar_t* content" is just a pointer that points to a non-shared data. You can make it like "wchar_t content[<yourlength>]" so the other processes can access the actual data correctly.

Hope it will help you

[Igor Vartanov]

#pragma data_seg("Shared")
volatile wchar_t* content; // !!! this sharing won't work
#pragma data_seg()
#pragma comment(linker, "/Section:Shared,RWS")

The problem with the code is that any unintialized global variable is placed into .bss section, disregarding pragma data_seg specifications. (Please note, data_seg, but not data_seq)

// 11.cpp
#pragma data_seg("Shared")
volatile wchar_t* content;
#pragma data_seg()
#pragma comment(linker, "/Section:Shared,RWS")

int main()
{
	return 0;
}

cl 11.cpp /link /map:11.map

 11

 Timestamp is 49c41c78 (Sat Mar 21 01:45:12 2009)

 Preferred load address is 00400000

 Start         Length     Name                   Class
 0001:00000000 00006254H .text                   CODE
 0002:00000000 000000f4H .idata$5                DATA
 0002:000000f4 00000004H .CRT$XCA                DATA
. . . 
 0002:0000152c 000000f4H .idata$4                DATA
 0002:00001620 00000452H .idata$6                DATA
 0002:00001a72 00000000H .edata                  DATA
 0003:00000000 00000cc0H .data                   DATA
 0003:00000cc0 00000bbcH .bss                    DATA

  Address         Publics by Value              Rva+Base       Lib:Object

 0000:00000000       __except_list              00000000     <absolute>
 0000:00000003       ___safe_se_handler_count   00000003     <absolute>
 0000:00000000       ___ImageBase               00400000     <linker-defined>
 0001:00000000       _main                      00401000 f   11.obj
 0001:00000222       _mainCRTStartup            00401222 f   LIBCMT:crt0.obj
. . .
 0003:00000c50       __lpdays                   0040ac50     LIBCMT:days.obj
 0003:00000c84       __days                     0040ac84     LIBCMT:days.obj
 0003:00000cc0       ?content@@3PC_WC           0040acc0     11.obj
 0003:00000cc4       __aenvptr                  0040acc4     LIBCMT:crt0.obj
 0003:00000cc8       __wenvptr                  0040acc8     LIBCMT:crt0.obj
 0003:00000ccc       ___error_mode              0040accc     LIBCMT:crt0.obj
 0003:00000cd0       __umaskval                 0040acd0     LIBCMT:crt0dat.obj
 0003:00000cd4       __osplatform               0040acd4     LIBCMT:crt0dat.obj
. . .