Qt 和 VS C++ dll函数返回值

发布于 2024-12-13 03:43:37 字数 551 浏览 4 评论 0原文

我正在尝试从 Qt 中连接的 DLL 获取 std::string/std::wstring 返回值，但我遇到了问题。

来自 DLL 的代码：

using namespace std;
extern "C++" __declspec(dllexport) string test()
{
    return "Passed!";
}

我的 Qt 应用程序（Qt Creator）中的代码：

typedef std::string (*Test)();
QLibrary *lib = new QLibrary("dllname");
lib->load();
.... dll load check ....
Test test = (Test) lib->resolve("test");
std::string s = test();
QString name = QString::fromStdString(s);

结果“name”变量将包含“H”而不是“Passed！” 我做错了什么？

提前致谢

原文

I'm trying to get std::string/std::wstring returned value from connected DLL in Qt and I having problem with this.

code from DLL:

using namespace std;
extern "C++" __declspec(dllexport) string test()
{
    return "Passed!";
}

code in my Qt application (Qt Creator):

typedef std::string (*Test)();
QLibrary *lib = new QLibrary("dllname");
lib->load();
.... dll load check ....
Test test = (Test) lib->resolve("test");
std::string s = test();
QString name = QString::fromStdString(s);

In result "name" variable will have "H" insted of "Passed!"
What I'm doing wrong?

Thanks in advance

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星光不落少年眉 2024-12-20 03:43:37

感谢您的评论，我已经做到了：

extern "C" __declspec(dllexport) int test(wchar_t* out)
{
    wcscpy_s(out, MAX_PATH, L"Passed!"); // I'm using sys paths in my app, 
                                           // so MAX_PATH is ok for me
    return 0;
}

Qt 端：

typedef int (*Test)(wchar_t*);
QLibrary *lib = new QLibrary("dllname");
lib->load();
.... dll load check ....
Test test = (Test) lib->resolve("test");
wchar_t s[MAX_PATH];
test(s);
QString name = QString::fromWCharArray(s);

变量“名称”现在应该是“通过！”

在 QLibrary 类参考中提到了仅支持

extern "C" __declspec(dllexport)

指令。

已更新谢谢@MSalters

Thanks for your comments, I've made it:

extern "C" __declspec(dllexport) int test(wchar_t* out)
{
    wcscpy_s(out, MAX_PATH, L"Passed!"); // I'm using sys paths in my app, 
                                           // so MAX_PATH is ok for me
    return 0;
}

Qt side:

typedef int (*Test)(wchar_t*);
QLibrary *lib = new QLibrary("dllname");
lib->load();
.... dll load check ....
Test test = (Test) lib->resolve("test");
wchar_t s[MAX_PATH];
test(s);
QString name = QString::fromWCharArray(s);

Variable "name" now should be "Passed!"

In QLibrary class reference says about support only