Qt调用dll

直接上代码

extern "C"{
DLLSHARED_EXPORT Dll* getDllObject(); //获取类Dll的对象
DLLSHARED_EXPORT void releseDllObject(Dll*); //获取类Dll的对象

DLLSHARED_EXPORT void helloWorld();
DLLSHARED_EXPORT int add(int a,int b);
}

#include "mainwindow.h"
#include <QApplication>
#include <iostream>
#include <QLibrary>
#include <windows.h>
#include "dll.h"  //头文件还是需要加的，否则无法解析Dll类

typedef Dll* (*CreatDll)();//定义函数指针,获取类Dll对象;
typedef bool (*ReleseDll)(Dll*);
typedef void (*fun)();

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();

    QLibrary mylib("dll.dll");   //声明所用到的dll文件
    //判断是否正确加载
    if (mylib.load())
    {
        std::cout << "DLL  loaded!"<<std::endl;
        CreatDll creatDll = (CreatDll)mylib.resolve("getDllObject");
        ReleseDll decDll=(ReleseDll)mylib.resolve ("releseDllObject");
        fun hello=(fun)mylib.resolve ("helloWorld");
        if(hello)hello();
        if(creatDll&&decDll)
        {
            Dll *testDll = creatDll();
            testDll->GetStrAdd ("abc","ABD");
            testDll->Print ();
            decDll(testDll);
        }
    }
    //加载失败
    else
        std::cout << "DLL is not loaded!"<<std::endl;

    mylib.unload ();

    return a.exec();
}

工程文件加入

#LIBS += "D:/qt_work/build-dllTest-Desktop_Qt_5_11_1_MinGW_32bit-Debug/debug/dll.dll" 或者
LIBS += D:\qt_work\build-dllTest-Desktop_Qt_5_11_1_MinGW_32bit-Debug\debug\dll.dll

否则会报错：

D:\qt_work\build-dllTest-Desktop_Qt_5_11_1_MinGW_32bit-Debug\debug\main.o:-1: In function
  `Z5qMainiPPc':
D:\qt_work\dllTest\main.cpp:30: error: undefined reference to
  `_imp___ZN3Dll9GetStrAddENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEES5_'
D:\qt_work\dllTest\main.cpp:31: error: undefined reference to `_imp___ZN3Dll5PrintEv'