.Net c++ multithreading using form1 generated code

[lewisms]

Hello all,

I am quite new to c++/. Net so please don't shoot me down for being a newbie. Any way I am trying to make a simple multithreading program that is just to learn the ideas behind it (before I incorporate them in another program). I just can’t seem to get a non-static call to work in my thread that has access to the Form1 variables and controls I need. I can call a non-static function using another class but then I can seem to get in to link to Form1 without creating a new instance (I don't want that as then it will not really work).

Below is my code using VC++ Express Edition on win xp pro

#pragma once
#include "Thread.h"//test header class not used
#include "stdafx.h"
#include <process.h>//multi-threading
#include <stdlib.h>
#include "windows.h"//windpws commands

//multi-threading
unsigned __stdcall MyThread1(void * param);
unsigned tid1; // thread IDs
HANDLE hMainThread; // thread handles
HINSTANCE hInst; // instance handle
HWND hwnd;

//namespace
using namespace System;
using namespace System::Windows;
using namespace System::ComponentModel;
using namespace System::Collections;
using namespace System::Windows::Forms;
using namespace System::Data;
using namespace System::Drawing;
#using <System.dll>
#using <System.Drawing.dll>
#using <System.Windows.Forms.dll>

namespace Multi_Thread_Test2 {

	#define  __stdcall
	
	using namespace System;
	using namespace System::ComponentModel;
	using namespace System::Collections;
	using namespace System::Windows::Forms;
	using namespace System::Data;
	using namespace System::Drawing;

	public ref class Form1 : public System::Windows::Forms::Form
	{
	public:
		Form1(void)
		{
			InitializeComponent();
			//
			//TODO: Add the constructor code here
			//
		}
	public:
		/// <summary>
		/// Clean up any resources being used.
		/// </summary>
		~Form1()
		{
			if (components)
			{
				delete components;
			}
		}
	public: System::Windows::Forms::Button^  Run;
	public: System::Windows::Forms::ProgressBar^  ProgressBar;
	
	public:
		
		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->Run = (gcnew System::Windows::Forms::Button());
			this->ProgressBar = (gcnew System::Windows::Forms::ProgressBar());
			this->SuspendLayout();
			// 
			// Run
			// 
			this->Run->Location = System::Drawing::Point(202, 61);
			this->Run->Name = L"Run";
			this->Run->Size = System::Drawing::Size(75, 23);
			this->Run->TabIndex = 0;
			this->Run->Text = L"Run";
			this->Run->UseVisualStyleBackColor = true;
			this->Run->Click += gcnew System::EventHandler(this, &Form1::Run_Click);
			// 
			// ProgressBar
			// 
			this->ProgressBar->Location = System::Drawing::Point(13, 12);
			this->ProgressBar->Name = L"ProgressBar";
			this->ProgressBar->Size = System::Drawing::Size(450, 43);
			this->ProgressBar->Step = 1;
			this->ProgressBar->TabIndex = 1;
			this->ProgressBar->Value = 1;
			// 
			// Form1
			// 
			this->AutoScaleDimensions = System::Drawing::SizeF(6, 13);
			this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;
			this->ClientSize = System::Drawing::Size(475, 95);
			this->Controls->Add(this->ProgressBar);
			this->Controls->Add(this->Run);
			this->Name = L"Form1";
			this->Text = L"Form1";
			this->ResumeLayout(false);

		}
#pragma endregion
	private: System::Void Run_Click(System::Object^  sender, System::EventArgs^  e)
			 {
				StartThreadFunc();
			 }
	public: void UpdateProgressBar()
			 {
				int i;
				for (i=0;i<100;i++)
				{
					System::Threading::Thread::Sleep(500);
					this->ProgressBar->Value = i;
				}
			 }
	public: void StartThreadFunc()
			{
			void ( *funcPtr)( ) =   &Multi_Thread_Test2::Form1::UpdateProgressBar; 
			 hMainThread = (HANDLE) _beginthreadex(NULL, 0, funcPtr, (void *) hwnd, 0, &tid1);
			}
	
	};// end class Form1 definition		
unsigned __stdcall MyThread1(void * param)//unused function
			 {	
				/*int i;
				for (i=0;i<100;i++)
				{
					System::Threading::Thread::Sleep(500);
					this->ProgressBar->Value = i;
				}*/
				/*Form1 MainForm;
				MainForm.UpdateProgressBar();*/
				return 0;
			 }

}//end multi_thread_test2

What i get as an output is

------ Rebuild All started: Project: Multi_Thread_Test2, Configuration: Debug Win32 ------
Deleting intermediate and output files for project 'Multi_Thread_Test2', configuration 'Debug|Win32'
Compiling...
stdafx.cpp
Compiling...
AssemblyInfo.cpp
Multi_Thread_Test2.cpp
c:\documents and settings\lspencer\my documents\visual studio 2005\projects\multi_thread_test2\multi_thread_test2\Form1.h(139) : error C3374: can't take address of 'Multi_Thread_Test2::Form1::UpdateProgressBar' unless creating delegate instance
c:\documents and settings\lspencer\my documents\visual studio 2005\projects\multi_thread_test2\multi_thread_test2\Form1.h(140) : error C2665: '_beginthreadex' : none of the 2 overloads could convert all the argument types
        C:\Program Files\Microsoft Visual Studio 8\VC\include\process.h(57): could be 'uintptr_t _beginthreadex(void *,unsigned int,unsigned int (__stdcall *)(void *),void *,unsigned int,unsigned int *)'
        C:\Program Files\Microsoft Visual Studio 8\VC\include\process.h(67): or 'uintptr_t _beginthreadex(void *,unsigned int,unsigned int (__clrcall *)(void *),void *,unsigned int,unsigned int *)'
        while trying to match the argument list '(int, int, void (__clrcall *)(void), void *, int, unsigned int *)'
Generating Code...
Build log was saved at "file://c:\Documents and Settings\lspencer\My Documents\Visual Studio 2005\Projects\Multi_Thread_Test2\Multi_Thread_Test2\Debug\BuildLog.htm"
Multi_Thread_Test2 - 2 error(s), 0 warning(s)
========== Rebuild All: 0 succeeded, 1 failed, 0 skipped ==========

I now the problem lies with

void ( *funcPtr)( ) =   &Multi_Thread_Test2::Form1::UpdateProgressBar; 
			 hMainThread = (HANDLE) _beginthreadex(NULL, 0, funcPtr, (void *) hwnd, 0, &tid1);

All help would be welcome. I have already tried using the CreateThread function to no luck.

[TRScheel]

You are creating a native pointer to reference the function. You need to create a managed pointer to use it.

Managed pointers are declared with ^ instead of *


I explain it in more detail on this thread:

Thread Regarding Native/Managed Pointers

[lewisms]

i managed to fix it in the end via changing the code to use

using namespace System::Threadi ng;

here it is, to help any one else

#pragma once

namespace Multi_Thread_Test2 {
	
	using namespace System;
	using namespace System::ComponentModel;
	using namespace System::Collections;
	using namespace System::Windows::Forms;
	using namespace System::Data;
	using namespace System::Drawing;
	using namespace System::Threading;

	/// <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();
		}	
	public:~Form1()
		{
			if (trd->IsAlive)
				trd->Abort();
			if (components)
			{
				delete components;
			}
		}	
	private: Thread ^trd;
	public: System::Windows::Forms::Button^  Run;
	public: System::Windows::Forms::ProgressBar^  ProgressBar;
	public:	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->Run = (gcnew System::Windows::Forms::Button());
				this->ProgressBar = (gcnew System::Windows::Forms::ProgressBar());
				this->SuspendLayout();
				// 
				// Run
				// 
				this->Run->Location = System::Drawing::Point(202, 61);
				this->Run->Name = L"Run";
				this->Run->Size = System::Drawing::Size(75, 23);
				this->Run->TabIndex = 0;
				this->Run->Text = L"Run";
				this->Run->UseVisualStyleBackColor = true;
				this->Run->Click += gcnew System::EventHandler(this, &Form1::Run_Click);
				// 
				// ProgressBar
				// 
				this->ProgressBar->Location = System::Drawing::Point(13, 12);
				this->ProgressBar->Name = L"ProgressBar";
				this->ProgressBar->Size = System::Drawing::Size(450, 43);
				this->ProgressBar->Step = 1;
				this->ProgressBar->TabIndex = 1;
				this->ProgressBar->Value = 0;
				// 
				// Form1
				// 
				this->AutoScaleDimensions = System::Drawing::SizeF(6, 13);
				this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;
				this->ClientSize = System::Drawing::Size(475, 95);
				this->Controls->Add(this->ProgressBar);
				this->Controls->Add(this->Run);
				this->Name = L"Form1";
				this->Text = L"Form1";
				this->ResumeLayout(false);

			}
#pragma endregion
	private: System::Void Run_Click(System::Object^  sender, System::EventArgs^  e)
			 {
			
				StartThreadFunc();
			 }
	
	public:  void UpdateProgressBar()
			 {
				int i;
				for (i=0;i<100;i++)
				{
					System::Threading::Thread::Sleep(500);
					this->ProgressBar->Value = i;
				}	
			 }
	public: void StartThreadFunc()
			{
				ThreadStart ^myThreadDelegate = gcnew ThreadStart(this, &Form1::UpdateProgressBar);
				trd = gcnew Thread(myThreadDelegate);
				trd->IsBackground = true;
				trd->Start();
			}

	};// end class Form1 definition	
}//end multi_thread_test2

I tried to use the ^ pointer but i kept getting two linking errors, oh well this method works fine.