I am attempting to figure out why calling a function in a dynamically loaded lib crashes python. I’m doing the following, I have a C++ function in a dynamic library file, which is loaded in python using ctypes. I then call the function from python: On MacOS, this works exactly as expected. Unfortunately…
Tag: ctypes
Add directory to PATH inside a Python script such that a third-party module can find a DLL with ctypes find_library
Let’s say a third-party module moduleXYZ.py (that I don’t want to fork/modify) does: In my code main.py I’m importing it with This DLL is in C:Program Filesgsgs9.56.1bin which is not in my global system path. Question: how to add this directory to the path (for the duration of the script run…
Wrapping a C++ library using msl-loadlib in python
I am currently writing a wrapper for a C++ library. The library is a 32-bits dll file and I’m using 64-bits so I’m using msl-loadlib. I have a problem wrapping a function that has pointer parameters. Here is the header of the function in C++ and here the wrapper I wrote When I call Client.getMeasu…
float pointer in ctypes python and pass structure pointer
I’m trying to pass a structure pointer to the API wrapper, Where the struct is containing float pointer member. I’m not sure that how we can pass float pointer value to the structure. /Structure/ /wrapper/ Answer You can either create a c_float instance and initialize with a pointer to that instan…
Get image from a fingerprint using Python and Ctypes
I’m trying to get an image from the fingerprint scanner Futronic FS88h, here is what I’ve been doing until now. With this I’m able to check if the finger is present and it actually retrieves some info, but I need to get the image from the device and I’m not quite sure how to do it, I&#…
Calling C++ function which accepts and returns std::string from Python
I’m trying to call C++ function using ctypes. The function declaration looks like As Python can not interact with C++ directly, I have created a C-wrapper for this function as follows And Python wrapper But when I try to call Python wrapper with some bytes passed as param, for example It fails with the …
How to convert a binary data into c_ubyte_Array_64 in python
How to convert ` b’x00x00x00x00x00x00x00x01′ c_ubyte_Array_64 in python. I could find any resources only so any help would really appreciated. I have to send this message which should be of type c_ubyte_Array_64 I tried it in the above manner but it gives me this error Answer Listing [Python.Docs]…
Pointer argument passing in python ctypes
I have the following c function. This function returns outbuf, the output length is unknown before calling the function so the function receives a pointer to the length as an argument outbuf_len, also the caller is responsible to free outbuf. I want to get the result of this function from python, so I started…
ModuleNotFoundError: No module named ‘_ctypes’ while installing libraries
I have not found any useful answers elsewhere, so I want to ask for help here. I’m trying to set up a VPS and I need some libraries (like datetime and random), however, when I type pip3.10 install datetime, it just gives me a bunch of errors: What should I do? Answer As it seems, you are trying to insta…
Python ctype Structure/Union Issue
So I am trying to do a bitmap. The data comes from a device as a 32bit number and each bit means something. So I was playing around with ctype Structures and Unions. Trying to do the classic int in and it maps to the individual bits. and this output. This first line is the 32bit value and the rest