Question

我在Visual Studio解决方案中有3个项目：

unmanaged_cpp ：构建本机C ++ DLL
managed_cpp ：构建使用.NET Framework的托管C ++ DLL
ConsoleApp ：本机C ++控制台应用程序

每个项目的代码如下所示：

unmanaged_cpp.dll

#include <string>

extern "C" __declspec(dllexport) int joinInt_Native(int x1, int x2) {
    std::string s1 = std::to_string(x1);
    std::string s2 = std::to_string(x2);
    std::string s = s1 + s2;
    return atoi(s.c_str());
}

managed_cpp.dll

extern "C" __declspec(dllexport) int joinInt_NetFramework(int x1, int x2) {
    System::String ^s = x1.ToString() + x2.ToString();
    return int::Parse(s);
}

ConsoleApp.exe

#include <iostream>
#include <Windows.h>
using namespace std;

typedef int(__cdecl *join_fn)(int, int);

HMODULE loadLibrary(LPCSTR dllName, LPCSTR func_name) {
    HMODULE dll_id = LoadLibraryA(dllName); //Assume always OK
    join_fn f_test = (join_fn)GetProcAddress(dll_id, func_name);
    cout << "Loaded DLL " << dllName << ", call = " << f_test(111, 222) << endl;
    return dll_id;
}

int main()
{
    char c;
    HMODULE id1, id2;
    cout << "ENTER: 1=load_DLL_1, 2=unload_DLL_1, 3=load_DLL_2, 4=unload_DLL_2, q=exit:" << endl;

    while ((c = cin.get()) != 'q') {
        switch (c)
        {

        // Load unmanaged_cpp.dll 
        case '1':
            id1 = loadLibrary("unmanaged_cpp.dll", "joinInt_Native");
            break;
        case '2':
            FreeLibrary(id1);
            break;

            // Load managed_cpp.dll 
        case '3':
            id2 = loadLibrary("managed_cpp.dll", "joinInt_NetFramework");
            break;
        case '4':
            FreeLibrary(id2);
            break;
        }
    }

    return 0;
}

现在，我构建并启动控制台应用程序，尝试这样的操作：

输入1 ==＆gt; Loaded DLL unmanaged_cpp.dll, call = 111222
尝试删除 unmanaged_cpp.dll ==＆gt; This action can't be completed because the file is open in ConsoleApp.exe ==＆gt;确定
输入2 ==＆gt;尝试删除 unmanaged_cpp.dll ==＆gt;文件可以删除 ==＆gt;确定
输入3 ==＆gt; Loaded DLL managed_cpp.dll, call = 111222
尝试删除 managed_cpp.dll ==＆gt; This action can't be completed because the file is open in ConsoleApp.exe ==＆gt;确定
输入4 ==＆gt;尝试删除 managed_cpp.dll ==＆gt; This action can't be completed because the file is open in ConsoleApp.exe ==＆gt;为什么？
等一下（可能是垃圾收集器发布的资源）==＆gt;尝试删除 managed_cpp.dll ==＆gt;仍然无法删除？
输入'q'==＆gt;控制台应用退出==＆gt;尝试删除 managed_cpp.dll ==＆gt;文件可以删除

为什么我无法释放托管DLL，因为我可以使用非托管DLL？如何处理这个问题？

只是另一个小问题，上面的代码是否正确？我查看“输出”窗口，它打印出类似这样的内容：

Loaded '...\Debug\unmanaged_cpp.dll'. Symbols loaded.
Unloaded '...\Debug\unmanaged_cpp.dll'
Loaded '...\Debug\managed_cpp.dll'. Symbols loaded.
Loaded many .NET DLL here...
Exception thrown at 0x7586A832 (KernelBase.dll) in ConsoleApp.exe: 0x04242420 (parameters: 0x31415927, 0x73850000, 0x004FEE10).
Loaded many .NET DLL here

控制台应用程序看起来工作正常，但此处抛出异常。那是为什么？

C ++无法卸载托管DLL

0 个答案: