来自 Python 的 C-API - 如何获取字符串？

Question

Euler Math Toolbox ( www.euler-math-toolbox.de ) has an interface with Python 2. Now it should interface with Python 3. But I seem to be unable to read output from Python. Below is a simple example of what I am trying to do. The code fails in the last step, PyBytes_AsString(). Probably, I am completely off track here.

Please advice.

---

#include <stdio.h>
#include <Python.h>

const char* pystart = "t = \"test\"";

int main()
{
    printf("Test Programm for Python 3.8\n");

    Py_Initialize();

    PyObject* pModule = PyImport_AddModule("__main__"); //create main module
    if (!pModule)
    {
        printf("Could not create main module in Python.");
        return 0;
    }

    if (PyRun_SimpleString(pystart) == -1)
    {
        printf("Could not run pystart.");
        return 0;
    }

    PyObject* t = PyObject_GetAttrString(pModule, "t");
    if (!t)
    {
        printf("Could not get t.");
        return 0;
    }
    char* out = PyBytes_AsString(t);
    if (!out)
    {
        printf("Could not get the string.");
        return 0;
    }
    printf(out);

    return 1;
}

Answer 1

The trick is, of course, to convert from unicode with PyUnicode_AsEncodedString(t,"utf-8","strict") before applying PyBytes_AsString().