Threading A function

This is a discussion on Threading A function within the Windows Programming forums, part of the Platform Specific Boards category; Hey, I have made a function that swaps 2 files around on an ftp server, of course it slows the ...

  1. #1
    Registered User (TNT)'s Avatar
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    Threading A function

    Hey,

    I have made a function that swaps 2 files around on an ftp server, of course it slows the prog down and i need to run the function in a seperate thread.

    i call the function like this:

    SwapFiles("ftp.mysite.com", "user1", "pass", 21, "htdocs/ss", "sstatus.asp", "sonline.asp");

    Inside swapfiles a connection is made to the server and then the files are swapped. How can i do all of this in a seperate thread?

    Thanks
    TNT
    TNT
    You Can Stop Me, But You Cant Stop Us All

  2. #2
    Registered User johnnie2's Avatar
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    You could change SwapFiles()'s declaration to DWORD WINAPI SwapFiles(LPVOID) and pass in a struct with members corresponding to the function's current parameters:

    Code:
    typedef struct {
       char site[64];
       char username[32];
       char password[32];
       int port;
       char path[128];
       char fileFrom[32];
       char fileTo[32];
    } swapInfo;
    
    
    swapInfo info;
    // fill in members as needed, etc.
    CreateThread(NULL, 0, SwapFiles, &info, 0);
    "Optimal decisions, once made, do not need to be changed." - Robert Sedgewick, Algorithms in C

  3. #3
    Has a Masters in B.S.
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    if your using windows look into beginthread() or beginthreadex() you will need to pass the params as a struct but it will allow multithreading!
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  4. #4
    It's full of stars adrianxw's Avatar
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    Yes, be carefull with that CreateThread() API if you are using a lot of the runtime library routines - they can cause memory leaks when used with CreateThread(). Use beginthread() or the ex version.
    Wave upon wave of demented avengers march cheerfully out of obscurity unto the dream.

  5. #5
    Registered User (TNT)'s Avatar
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    Hey,

    Thanks alot for that, i think im going to use the createthread() method, but i just have a question.

    How do i access the structure in SwapFiles()?

    DWORD WINAPI SwapFiles(LPVOID);

    and im passing it the structure, how do i then access the struct inside the function.

    Also i need the function to return an int?

    Thanks
    TNT
    Last edited by (TNT); 06-06-2002 at 07:11 AM.
    TNT
    You Can Stop Me, But You Cant Stop Us All

  6. #6
    Registered User johnnie2's Avatar
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    You'd need to cast the parameter passed to SwapFiles() to get access to the struct:

    Code:
    DWORD WINAPI SwapFiles(LPVOID lParam) {
       swapInfo *thisSwap = (swapInfo *)lParam;
    
       connectToServer(thisSwap->site);
       // and so on
    
       return 0;
    }
    And yes, it's expected to return some kind of value at the end.

    Using CreateThread() while calling library routines may result in a memory leak of 70-80 bytes when ExitThread() is called, so consider _beginthread() under those circumstances.
    "Optimal decisions, once made, do not need to be changed." - Robert Sedgewick, Algorithms in C

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