koobas.hobune.stream
Converting from c# string to c++ string
I'm using a Dll created from a C++ file. When I either put the .dll and .lib files in my Unity-project folder or when I use the function that I need, Unity crashes and I can't open the project untile I remove the .dll or delete the function from the c# script.
This function works well on C++, both in Visual Studio and in Dev-C++
PS: Assets/alzBraccioCorretto.json is the file that I need to read
I've tried the same procedure for more simple dlls (just functions with int or double variables) and it worked fine, so I don't know what I'm missing with this one, probably UNICODE
In the Unity script I wrote
[DllImport("QuartaLibreria.dll", CharSet = CharSet.Unicode)]
static extern string LeggiFile(string nomeFile);
Text testo;
unsafe void Start()
{
testo = GetComponent<Text>();
temp = LeggiFile("Assets/alzBraccioCorretto.json");
testo.text = temp;
}
In the header of the library I have
#define QUARTALIBRERIA_API __declspec(dllexport)
//all the other headers and #include
string leggiFile(char* nomeFile);
extern "C" {
QUARTALIBRERIA_API wstring LeggiFile(wstring nomeFile);}
In the cpp of the library I have
string leggiFile(string nomeFile) {
ifstream _stream(nomeFile.c_str());
string temp;
_stream >> temp >> temp;
_stream.close();
return temp;
}
QUARTALIBRERIA_API wstring LeggiFile(wstring nomeFile){
std::string str(nomeFile.begin(), nomeFile.end());
string daRit = leggiFile(str);
std::wstring WdaRit(daRit.length(), L' '); // Make room for characters
std::copy(daRit.begin(), daRit.end(), WdaRit.begin());
return WdaRit;
}
You can not return a string from a native code method. Inside .NET managed land memory has to be managed memory. Have a look at this SO question. If you want to return string data to C# you should reverse the ownership. So you have to allocate the buffer memory on the managed side and pass a pointer to the native method which can fill the the buffer.
Though your code looks a bit strange. Why would you pass a file name to a native code plugin to read the content and then just return that content back to native code?
The code was just a sample for a more complex function. No need to return a string, but I need to give it as an input because I need to read a file with ifstream using the dll. Thank you for your help! I'll try my best and I'll let you know!
