How to call static DWORD WINAPI ThreadFunc(LPVOID pvParam)
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Thread: How to call static DWORD WINAPI ThreadFunc(LPVOID pvParam)

  1. #1
    Join Date
    Feb 2007
    Posts
    39

    Question How to call static DWORD WINAPI ThreadFunc(LPVOID pvParam)

    I am facing a problem:

    I have say 3 files :

    ABC.h ----- this file has the function prototypes
    ABC.cpp ------ the definitions of the functions
    ABC_Test.cpp ------- the file with main() which calls the functions using ABC's object say "ob".


    Now I want to make a function say "startNewThread()" inside ABC.cpp and its prototype in ABC.h, then where should I define

    static DWORD WINAPI ThreadFunc(LPVOID pvParam);

    function. Inside ABC_Test.cpp or inside ABC.cpp

    Also Iwill call the createThread() of Win API inside startNewThread() and pass the ThreadFunc as one of its parameters. If this is possible, then its OK. But if I have to call some function of mine say

    void ABC :: printXYZ() inside ThreadFunc , then how can I do this. I do not have my object say ABC ob; i.e. "ob" inside my ThreadFunc.

    Please reply, if possible with a EXAMPLE code

    Pawan
    Life is like a box of chocolates,
    You never know what you are going to get,
    But as it is a box of chocolates,
    Everything coming out of it will be sweet.

  2. #2
    Join Date
    Aug 2005
    Posts
    478

    Re: How to call static DWORD WINAPI ThreadFunc(LPVOID pvParam)

    http://msdn2.microsoft.com/en-US/library/ms682453.aspx

    So you should cast your 'ob' instance to lpParameter.

    Code:
    CreateThread( ..., ( LPVOID ) &ob, ... );
    
    ...
    
    
    static DWORD WINAPI ThreadFunc(LPVOID pvParam)
    {
            ABC * ob = ( ABC * ) pvParam;
    }
    Windows XP, Visual Studio 2008, SVN

  3. #3
    Join Date
    Feb 2007
    Posts
    39

    Question Re: How to call static DWORD WINAPI ThreadFunc(LPVOID pvParam)

    I have tried thiss, and its a success when I just want send an object to the threadFucn() but the problem I am facing is :

    I have a socket object say : clientSocket and I am sending this to the threadFunc() as the parameter in CreateThread(). But how can I send more than 1 parameter to the threadFunc() using CreateThread(). For example both clientSocket object and my ABC ob.

    Pawan
    Life is like a box of chocolates,
    You never know what you are going to get,
    But as it is a box of chocolates,
    Everything coming out of it will be sweet.

  4. #4
    Join Date
    Mar 2002
    Location
    NY, USA
    Posts
    12,097

    Re: How to call static DWORD WINAPI ThreadFunc(LPVOID pvParam)

    But how can I send more than 1 parameter to the threadFunc() using CreateThread().
    Not complete/compilable code, but to illustrate the point....
    Code:
    class Info
    {
    public:
       SomeClass1 thing1;
       SomeClass2 thing2;
       int value1;
       int value2;
    };
    
    
    {
    Into i;
    CreateThread(&i);
    }
    TheCPUWizard is a registered trademark, all rights reserved. (If this post was helpful, please RATE it!)
    2008, 2009
    In theory, there is no difference between theory and paractice; in practice there is.

    * Join the fight, refuse to respond to posts that contain code outside of [code] ... [/code] tags. See here for instructions
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  5. #5
    Join Date
    Feb 2007
    Posts
    39

    Question Re: How to call static DWORD WINAPI ThreadFunc(LPVOID pvParam)

    Here's everything in more detail :

    The 3 file are :
    1) GridServer.h containing function prototypes
    Code:
    DWORD WINAPI runThread(LPVOID Parameter);
    void startNewThread(SOCKET c_socket);
    2) GridServer.cpp ---- the .cpp file with function definitions

    Code:
    DWORD WINAPI GridServer :: runThread(LPVOID Parameter)
    {
    	//Get the information about client entity
    	SOCKET clientSocket = (SOCKET)Parameter;
    
        printf( "\n New Client Connected.\n");
    	cout.flush();
    
    	int bytesRecv = SOCKET_ERROR;
        char  *recvbuf;
    	recvbuf = new char[1];
    	
        int ch ;
        bytesRecv = recv( clientSocket, recvbuf, 1, 0 );
    	cout.flush();
    
        printf( "\n Bytes Received: %ld", bytesRecv );
    	printf("\n Data Received = %c", recvbuf[0]);
    	
    	ch = atoi(recvbuf);
    	
    	
    	switch(ch)
    	{
    		case 1	:	getFile(clientSocket);
    					break;
    		case 2  :	createAccount(clientSocket,TABLE_OF_INTEREST);
    					break;
    		default	:	printf("\n Invalid option sent from client.");
    					break;
    	}
    	
    	return 0;
    }
    
    /******************/
    void GridServer :: startNewThread(SOCKET c_socket)
    {
    	
    	HANDLE hThread;	//Handle to thread
    	DWORD ThreadId;	//used to store the thread id
    
    
    /********************/
    /***This is line 207 where error occurs****/
    /***************************/
    	/*Line207*/hThread = CreateThread(	NULL,
    							0,
    							&GridServer::runThread,
    							(LPVOID)c_socket,
    							0,
    							&ThreadId);
    
    	//printf("\n After CreateThread()");
    	return;
    
    }

    and
    3) GridServer_Test.cpp ---- the .cpp with main()

    it makes a GridServer object named : "ob" and calls
    Code:
    ob.startNewThread(acceptSocket);
    here acceptSocket is a variable of type SOCKET.

    now the problems are :

    when I compile the code, I get the following error :

    Code:
    g:\smartsafe\gridserver\gridserver.cpp(207) : error C2664: 'CreateThread' : cannot convert parameter 3 from 'DWORD (__stdcall GridServer::* )(LPVOID)' to 'LPTHREAD_START_ROUTINE'
            There is no context in which this conversion is possible
    What should I do?
    What I require are :
    1) calling the runThread() function properly from startNewThread() using CreateThread().
    2)Also if you can see that I am calling getFile() and createAccount() from inside the runThread() I want this to be called, with respect to the object which called startNewThread().

    I think I have tried to make my code clear this time.
    Please Reply, if more information is required, I will reply
    Pawan
    Last edited by ppuniversal; February 18th, 2007 at 07:38 AM. Reason: Line Number written inside code where error occurs.
    Life is like a box of chocolates,
    You never know what you are going to get,
    But as it is a box of chocolates,
    Everything coming out of it will be sweet.

  6. #6
    Join Date
    Mar 2002
    Location
    NY, USA
    Posts
    12,097

    Re: How to call static DWORD WINAPI ThreadFunc(LPVOID pvParam)

    Do me a favor and go back and edit your post to highlight the line which the error occurs on. I have problems counting to 207
    TheCPUWizard is a registered trademark, all rights reserved. (If this post was helpful, please RATE it!)
    2008, 2009
    In theory, there is no difference between theory and paractice; in practice there is.

    * Join the fight, refuse to respond to posts that contain code outside of [code] ... [/code] tags. See here for instructions
    * How NOT to post a question here
    * Of course you read this carefully before you posted
    * Need homework help? Read this first

  7. #7
    Join Date
    Feb 2007
    Location
    Munich, Germany
    Posts
    16

    Re: How to call static DWORD WINAPI ThreadFunc(LPVOID pvParam)

    I haven'T looked at the code, only at the error message.

    Your problem is that you want to cast a c++ member function pointer to a static C-style pointer. and this is forbidden, and there is NO way to work around this but one secret hack, and if you would really find this secret hack then it would crash

    You have two possibilities:

    1. use a static C function for the callback

    2. use a static C++ member function for the callback

    void
    function(void) // that's ok
    {
    }

    class C
    {
    static void member(void); // that's ok
    void member(void); // forbidden
    };

    more information about function pointers and why they are tricky with C++:
    http://www.newty.de/fpt/index.html

    HTH
    chris

  8. #8
    Join Date
    Feb 2007
    Posts
    39

    Re: How to call static DWORD WINAPI ThreadFunc(LPVOID pvParam)

    Quote Originally Posted by TheCPUWizard
    Do me a favor and go back and edit your post to highlight the line which the error occurs on. I have problems counting to 207

    I have added the line number where error occurs. Now please reply.
    Pawan
    Life is like a box of chocolates,
    You never know what you are going to get,
    But as it is a box of chocolates,
    Everything coming out of it will be sweet.

  9. #9
    Join Date
    Feb 2007
    Posts
    39

    Question Re: How to call static DWORD WINAPI ThreadFunc(LPVOID pvParam)

    I will study the "newty" links on function pointers, but can anyony reply to the answers which I have posted. They were :

    What I require are :
    1) calling the runThread() function properly from startNewThread() using CreateThread().
    2)Also if you can see that I am calling getFile() and createAccount() from inside the runThread() I want this to be called, with respect to the object which called startNewThread().
    Please tell me how to get these 2 things done.
    Pawan
    Life is like a box of chocolates,
    You never know what you are going to get,
    But as it is a box of chocolates,
    Everything coming out of it will be sweet.

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