Using dll + lib files in Qt Application



  • Hi all,

    I have the following issue. I want to use one external library which was written in FORTRAN. The guys which provide the library simply provide two files -- one dll and one lib file. I have a very detailed description of the functions inside the library but I don't know how to use it. I've already prepared one simple console application. In the .pro file I've added:
    @LIBS += "C:\Documents and Settings\Vasil.Yordanov\My Documents\Qt working\Siftool\libs\siftooldll.lib"@
    and
    @INCLUDEPATH += "C:\Documents and Settings\Vasil.Yordanov\My Documents\Qt working\Siftool\libs"@
    I also placed the siftooldll.dll into the included folder. When I run the console application with only these two lines added to the pro file it compiles with no error but I still don't know if I can use the functions inside the library ... and more specifically I don't how how exactly I should call them.

    Thanks in advance!



  • If it is compiled without errors, your library is linked successfully!

    bq. I have a very detailed description of the functions inside the library but I don't know how to use it.

    Functions or classes/interfaces? I guess it is collection of exported functions. You need to check if this exported functions are decorated or not. For example with this program: "DLL Export Viewer":http://www.nirsoft.net/utils/dll_export_viewer.html

    If exported functions are mangled, you should use following method to declare this functions:
    @__declspec(dllimport) int SomeFunctionFromLib(); // somewhere in header@
    after that you can use it as usual: @int i = SomeFunctionFromLib();@

    if functions in lib are unmangled you should better load this library dynamical instead of linking it.
    And use "QLibrary":http://qt-project.org/doc/qt-4.8/qlibrary.html to resolve functions:
    @
    QLibrary myLib("mylib");
    typedef void (*MyPrototype)();
    MyPrototype myFunction = (MyPrototype) myLib.resolve("mysymbol");
    if (myFunction)
    myFunction();
    @


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