How To Load (C++) Library in QT and Call function ?

[Taz742]

bool GlobalAll::WhatisMyIP(std::wstring& out_name )
{
    typedef bool (* LPDLLFUNC) (std::wstring&);

    QLibrary lib("ELService.dll");
    lib.load();

    if(lib.isLoaded())
        qDebug() << "its loaded";

    HINSTANCE hDLL;
    LPDLLFUNC lpfnDllFunc = NULL;

    if(!hDLL )
        return false;

    lpfnDllFunc = (LPDLLFUNC)lib.resolve("WhatIsMyIP");
    if(!lpfnDllFunc )
        return false;

    lpfnDllFunc(out_name);

    qDebug() << QString::fromStdWString(out_name);

    return true;
}

[m.sue]

Hi @Taz742

There is just one problem. This is a C interface. So, no reference, no bool, no classes, etc.

Just pointers and C standard types. If some C++ types work anyway, please consider it as a happy co-incidence that may not work on someone else's machine.

-Michael.

[Taz742]

@m.sue
I can not understand exactly what you want to say.
Can you write any example?

[m.sue]

Hi @Taz742

Your code is correct, but you can only use C standard types or pointers to such types.

typedef bool (* LPDLLFUNC) (std::wstring&);
->
typedef int (* LPDLLFUNC) (char *, int len);

You maybe lucky that a class pointer works but I would not bet on it.

-Michael.

[Taz742]

@m.sue

bool GlobalAll::GetContactNameByID(string tin, std::wstring& out_name )
{
    typedef bool (* LPDLLFUNC) (string, string, string, std::wstring&);

    HINSTANCE hDLL;
    LPDLLFUNC lpfnDllFunc = NULL;

    hDLL = LoadLibrary (L"C:\\Users\\tleladze\\Desktop\\build-user_-Desktop_Qt_5_7_0_MinGW_32bit-Debug\\debug\\ELService.dll");
    wstring sName;

    if(!hDLL )
        return false;

    lpfnDllFunc = (LPDLLFUNC)GetProcAddress(hDLL, "GetContactNameByID");
    if(!lpfnDllFunc )
        return false;

    lpfnDllFunc("arkania:206322102", "123456", tin, out_name);

    FreeLibrary (hDLL);

    return true;
}

i copy this code, and it worked fine in c++. but QT not.