.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::Threading;

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.