PyDict_GetItemString返回NULL

Question

我想从C程序中调用python函数，但是PyDict_GetItemString总是返回NULL，因此程序会写“函数出错”。 main_module和main_dict不是NULL，我已经检查了它。

我尝试实现此处的代码 Call a Python function from within a C program

test.c file:
 #include <stdlib.h>
 #include "python3.7m/Python.h"

int main() {
    PyObject* main_module = NULL;
    PyObject* main_dict = NULL;
    PyObject* function = NULL;
    Py_Initialize();
PyObject* sys = PyImport_ImportModule("sys");
PyObject* path = PyObject_GetAttrString(sys, "path");
PyList_Append(path, PyUnicode_FromString("."));
PyObject* pName = PyUnicode_FromString("test");
main_module = PyImport_Import(pName);
main_dict = PyModule_GetDict(main_module);
char* func_name = "multiply";
function = PyDict_GetItemString(main_dict, func_name);
if (!function) {
    printf("%s\n", "Something wrong in function");
}
Py_Finalize();
return 0;
}

test.py file:
def multiply():
    return int(2*2)


compilation:
gcc test.c -o test -lpython3.7m -I /usr/lib/python3.7 -I /usr/include/python3.7m