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This is a discussion on Thread within the C++ Programming forums, part of the General Programming Boards category; Hello All, I am learning how to use the TThread class to create another thread from my mainform. Essentially, I ...

  1. #1
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    Join Date
    Feb 2002
    Posts
    29

    Angry Thread

    Hello All,

    I am learning how to use the TThread class to create
    another thread from my mainform. Essentially, I am writing
    a file/folder search program that uses a recursive function
    called vSearch_Folder( ....) which takes 4 parameters. I am calling
    this function within the Execute method of the thread object, using the code below:-


    void __fastcall searchThread::Execute()
    {
    FreeOnTerminate = false;

    // call search functions
    mainform->vSearch_Folder(THREAD_FolderPath,
    THREAD_SearchString,
    THREAD_iSwitch,
    pTHREAD_iCounter);

    // free up memory for thread object
    FreeOnTerminate = true;
    }

    I am using a flag, FreeOnTerminate, to determine when the thread
    has finished execution. (ie when the recursive function has finished.)
    THe value of this flag is determined in mainform by calling inline

    bool bGetThreadStatus(void){return FreeOnTerminate;};

    which is declared in the class derived from TThread.



    Q. Is there a better way to determine when a thread finishes execution ?

    Thanks,


    bigSteve

  2. #2
    &TH of undefined behavior Fordy's Avatar
    Join Date
    Aug 2001
    Posts
    5,789

    Re: Thread

    Originally posted by bigSteve
    Hello All,

    I am learning how to use the TThread class to create
    another thread from my mainform. Essentially, I am writing
    a file/folder search program that uses a recursive function
    called vSearch_Folder( ....) which takes 4 parameters. I am calling
    this function within the Execute method of the thread object, using the code below:-


    void __fastcall searchThread::Execute()
    {
    FreeOnTerminate = false;

    // call search functions
    mainform->vSearch_Folder(THREAD_FolderPath,
    THREAD_SearchString,
    THREAD_iSwitch,
    pTHREAD_iCounter);

    // free up memory for thread object
    FreeOnTerminate = true;
    }

    I am using a flag, FreeOnTerminate, to determine when the thread
    has finished execution. (ie when the recursive function has finished.)
    THe value of this flag is determined in mainform by calling inline

    bool bGetThreadStatus(void){return FreeOnTerminate;};

    which is declared in the class derived from TThread.



    Q. Is there a better way to determine when a thread finishes execution ?

    Thanks,


    bigSteve
    Yes.........unless you mark FreeOnTerminate as a "volatile", there's no guarantee that your code will work. 1 standard unprotected variable accessed by 2 threads is often a recipie for disaster!

    A better way is for you to use one of window's thread sync objects...Events (with CreateEvent()) or Mutexes (CreateMutex()) are good possibilities depending on what you want to do

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