os.chdir() 通过 c++ 调用时出错

Question

I've wrote this code to change the working directory of the python to the c++ directory:

Py_Initialize();

// Get the c++ working directory
QString working_directory = QFileInfo(".").absolutePath();
qDebug() << "C++ wd: " << working_directory;

PyRun_SimpleString("import os");

// Import the os module
PyObject* pyOSModule = PyImport_ImportModule("os");
// Convert the std::string to c string
const char * wdCString = working_directory.toStdString().c_str();
// Create python working directory string
PyObject* pyWd = PyUnicode_FromString(wdCString);
// The chdir function of the os module
PyObject* pyChdirFunction = PyObject_GetAttrString(pyOSModule,(char*)"chdir");

// Call the chdir method with the working directory as argument
PyObject_CallFunction(pyChdirFunction, "s", pyWd);
PyRun_SimpleString("print('Python wd: ' + os.getcwd())");

The output is:

C++ wd:  "Q:/Q/UVC Luftreinigungsanlage/System/Air Purification Management System"
OSError: [WinError 123] The filename, directory name, or volume label syntax is incorrect: '\x01'

The strange thing is that with normal python shell "Q:/Q/UVC Luftreinigungsanlage/System/Air Purification Management System" is a valid string for os.chdir() and this works, but I see no difference to this called with the Python.h library.

Answer 1

wdCString is a dangling pointer - working_directory.toStdString() is a temporary object whose lifetime has ended at the next line.

You can either extend its lifetime,

const std::string& wd = working_directory.toStdString();
const char * wdCString = wd.c_str();

or pass the pointer directly,

PyObject* pyWd = PyUnicode_FromString(working_directory.toStdString().c_str());