QLibrary resolve returns false

I´m trying to inc开发者_Go百科lude classfiles dynamically right now and chose to do so by loading the .dll into a QLibrary. The problem I´m having now is, that when I try to call the resolve()-method it returns 0.

EDIT: In the meantime the problem has been solved and I decided to edit the code, so others can see how it works:

This is the .dll´s header file:

#ifndef DIVFIXTURE_H
#define DIVFIXTURE_H

#include<QObject>
#include<QVariant>

class __declspec(dllexport) DivFixture : public QObject
{
    Q_OBJECT
public:
    Q_INVOKABLE DivFixture();
    Q_INVOKABLE void setNumerator(QVariant num);
    Q_INVOKABLE void setDenominator(QVariant denom);
    Q_INVOKABLE QVariant quotient();

private:
    double numerator, denominator;
};

#endif

this is the dll´s .cpp-file:

#include "testfixture.h"

DivFixture::DivFixture(){}

void DivFixture::setNumerator(QVariant num)
{
    numerator=num.toDouble();
}


void DivFixture::setDenominator(QVariant denom)
{
    denominator=denom.toDouble();
}


QVariant DivFixture::quotient()
{
    QVariant ret;
    ret=numerator/denominator;
    return ret;
}

//non-class function to return pointer to class
extern "C" __declspec(dllexport) DivFixture* create()
{
   return new DivFixture();
}

And this is how I load my class:

currentFixture.setFileName("C:\\somepath\\testFixture.dll");
if(currentFixture.load());
{
    typedef QObject* (*getCurrentFixture)();
    getCurrentFixture fixture=(getCurrentFixture)currentFixture.resolve("create");
    if (fixture)
    {
        Fixture=fixture();
    }
}

---

You need to export your class using __declspec(dllexport)

class __declspec(dllexport) DivFixture : public QObject
{

---

The accepted answer isn't correct. __declspec has two possible parameters:

• dllexport
• dllimport

dllexport being used when compiling the library and dllimport when linking to it.

Qt already provides defines for that:

• Q_DECL_EXPORT
• Q_DECL_IMPORT

To make proper use of them, add something like:

#if defined(MYSHAREDLIB_LIBRARY)
#  define MYSHAREDLIB_EXPORT Q_DECL_EXPORT
#else
#  define MYSHAREDLIB_EXPORT Q_DECL_IMPORT
#endif

to a global header in your project that you will include in all classes you want to export. Then modify your classes so in the end the declaration looks like:

class MYSHAREDLIB_EXPORT DivFixture : public QObject

A complete example and more information are given in the Creating Shared Libraries of Qt's documentation.