C++ 一些奇怪的腐败问题

下面是我为通过串行端口输出可视数据而修改的winamp插件的一些片段

char * overrideCom = NULL;
char * cPortName;

void config(struct winampVisModule *this_mod)
{
    MessageBox(this_mod->hwndParent, cPortName, "Serial Port", MB_OK); // Tell us what the value is
}

// This function will convert a System^ string into a std::string
std::string makeStd(String ^in){
    array<Byte, 1> ^chars = System::Text::Encoding::ASCII->GetBytes(in);
    pin_ptr<Byte> charsPointer = &(chars[0]);
    char *nativeCharsPointer = reinterpret_cast<char *>(static_cast<unsigned char *>(charsPointer));
    std::string native(nativeCharsPointer, chars->Length);
    return nativeCharsPointer;
}

// This function will grab the second indexed com port and return it in an easily convertable std::string instead of String^
std::string getComPort(){
    array<String^, 1> ^serialPorts = nullptr;
    LPTSTR out;
    try {
        serialPorts = SerialPort::GetPortNames();
    }
    catch (Win32Exception^ ex)
    {
        MessageBox(NULL, "Failed to find COM port!","Initialize Failed!", MB_OK);
    }

    std::string portb = makeStd(serialPorts[1]);
    out = const_cast<char *>(portb.c_str());
    // Make sure I'm not crazy:
    MessageBox(NULL, out, "Com port!", MB_OK);
    return portb;
}

int init(struct winampVisModule *this_mod)
{
    config_read(this_mod);

    //std::string port = getComPort();
    //cPortName = const_cast<char *>(port.c_str());

    // This would normally work but for some reason causes corruption of the string and doesn't connect properly:

    if (overrideCom == NULL || overrideCom[0] == 0){
        std::string portx = getComPort();
        cPortName = const_cast<char *>(portx.c_str());
    }
    else
    {
        cPortName = overrideCom;
    }

return 0;
}

void config_getinifn(struct winampVisModule *this_mod, char *ini_file)
{   // makes a .ini file in the winamp directory named "plugin.ini"
    char *p;
    GetModuleFileName(this_mod->hDllInstance,ini_file,MAX_PATH);
    p=ini_file+strlen(ini_file);
    while (p >= ini_file && *p != '\\') p--;
    if (++p >= ini_file) *p = 0;
    strcat(ini_file,"plugin.ini");
}


void config_read(struct winampVisModule *this_mod)
{
    char ini_file[MAX_PATH];
    char* tResult = new char[255];
    config_getinifn(this_mod,ini_file);
    config_x = GetPrivateProfileInt(this_mod->description,"Screen_x",config_x,ini_file);
    config_y = GetPrivateProfileInt(this_mod->description,"Screen_y",config_y,ini_file);
    // Grab the overrideCom= param.
    GetPrivateProfileString(this_mod->description, "overrideCom", NULL, tResult, 255, ini_file);
    overrideCom = tResult;
}

当我省略上面的if语句时，config（）输出：

我不明白

而且， 当在INI文件中指定overrideCom参数时，它可以正常工作

我的目标是不依赖INI文件，允许它自动检测第二个com端口，但允许在需要时覆盖INI

---

DOH！解决方案是将portx声明为全局变量。

std:：string portx=getComPort（）；
std::string portx = getComPort();
cPortName = const_cast<char *>(portx.c_str());

cPortName=const_cast（portx.c_str（））；

---

在下一行，

portx

会被销毁，它的数据也会被销毁。因此，

cPortName

只是一个不指向任何东西的悬空指针。

Microsoft已经为您的

MakeStd

函数提供了一个更好的版本--

marshall\u as

。例如，通过包含正确的头文件，您可以执行

marshal\u as（dotnetString）

if (overrideCom == NULL || overrideCom[0] == 0){
    std::string portx = getComPort();
    cPortName = const_cast<char *>(portx.c_str());
}
else
{
    cPortName = overrideCom;
}

Èêtw

COM3

std::string portx = getComPort();
cPortName = const_cast<char *>(portx.c_str());