Return to Foreign Function Interface (FFI)

ctypes is a foreign function library for the Python programming language. It provides C-compatible data types and allows calling functions in DLLs or shared libraries. It can be used to wrap these libraries in pure Python.

• **C-Compatible Data Types:** ctypes provides a set of C-compatible data types, including integers, floating-point numbers, pointers, arrays, and structures. This allows Python to interact with C libraries in a natural way.
• **Function Calling:** ctypes allows calling functions in DLLs or shared libraries, passing arguments and receiving return values. This makes it possible to access functionality that is not available in pure Python.
• **Library Wrapping:** ctypes can be used to wrap C libraries in pure Python, providing a Pythonic interface to the library's functionality. This makes the library easier to use and integrate with other Python code.
• **Error Handling:** ctypes provides mechanisms for handling errors that occur during function calls, such as invalid arguments or exceptions raised in the C code.
• **Platform Independence:** ctypes is designed to be platform-independent, allowing the same Python code to work on different operating systems.

• **Official Documentation:** s://docs.python.org/3/library/ctypes.html(https://docs.python.org/3/library/ctypes.html)

```python import ctypes

1. Load the C library

libc = ctypes.CDLL(“libc.so.6”)

1. Define the argument and return types of the C function

libc.printf.argtypes = [ctypes.c_char_p] libc.printf.restype = ctypes.c_int

1. Call the C function

libc.printf(b“Hello, world!\n”) ```

In this example, `ctypes` is used to load the C standard library (`libc.so.6`) and call the `printf` function. The `argtypes` and `restype` attributes are used to specify the argument and return types of the `printf` function, respectively. The `b“Hello, world!\n”` argument is a bytes object that represents the string to be printed.