A simple example for calling C++ functions in Python by ctypes.


  • call C++ function int bar(int* value, char* msg) with argumenets:
  • call C++ function int foo(Foo* foo) with pointer to custom structure Foo
  • call C++ function int register_bar_callback(CALLBACK cb) with a C callable function pointers from Python callables (a.k.a, register a callback function)


cd ctypes-example
# build shared library
mkdir build && cd build
cmake ..
# test calling in Python
cd ../python
python test_foo.py


Outputs from register_bar_callback test:

$ python test_foo.py
=== Running test_callback() in Python ===
Calling register_bar_callback() in Python
register_bar_callback() called in C++
-> len_buf in C++ before callback: 10
-> buf in C++ before callback: 012345678
-> calling registered function in C++
Callback called in Python
-> len_buf received in Python: 10
-> len_buf modified in Python 13
-> buf modified in Python: Hello, World!
-> lem_buf in C++ aftering callback: 13
-> buf in C++ aftering callback: Hello, World!
Return value in Python: 0


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