How do i convert python code to c?

I know this is an older thread but I wanted to give what I think to be helpful information.

I personally use PyPy which is really easy to install using pip. I interchangeably use Python/PyPy interpreter, you don't need to change your code at all and I've found it to be roughly 40x faster than the standard python interpreter (Either Python 2x or 3x). I use pyCharm Community Edition to manage my code and I love it.

I like writing code in python as I think it lets you focus more on the task than the language, which is a huge plus for me. And if you need it to be even faster, you can always compile to a binary for Windows, Linux, or Mac (not straight forward but possible with other tools). From my experience, I get about 3.5x speedup over PyPy when compiling, meaning 140x faster than python. PyPy is available for Python 3x and 2x code and again if you use an IDE like PyCharm you can interchange between say PyPy, Cython, and Python very easily (takes a little of initial learning and setup though).

Some people may argue with me on this one, but I find PyPy to be faster than Cython. But they're both great choices though.

Edit: I'd like to make another quick note about compiling: when you compile, the resulting binary is much bigger than your python script as it builds all dependencies into it, etc. But then you get a few distinct benefits: speed!, now the app will work on any machine (depending on which OS you compiled for, if not all. lol) without Python or libraries, it also obfuscates your code and is technically 'production' ready (to a degree). Some compilers also generate C code, which I haven't really looked at or seen if it's useful or just gibberish. Good luck.

Hope that helps.

a lot of people use Cython to compile their python code in C for performance gains. It’s petty easy to do and might be something that you want to take advantage of.

Make sure you pip install Cython first.

The overall process goes like this.

• Bring the parts of your code you want to convert to c into a separate file
• Give type information and let Cython know what you want to use in Python and what you don’t.
• compile the separate file using a setup.py file

For this example, let’s say we want to compile this function into C

def AddToTen():
    x = 0for i in range(1,11):
        x+=i
    return x

The first thing we need to do is move this from a .py file into a .pyx file, which is what Cython uses. Now we are going to give type information to our variables

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in Cython, there are three def statements

• cdef: declaring something that is only going to be used in c(like the variables inside our function)
• pdef: declaring something that is only going to be used in Python
• cpdef: declaring something this going to be used in both

cpdef int AddToTen():
    cdef int x = 0
    cdef int ifor i in range(1,11):
        x+=i
    return x

Since I’m not going to call the variables inside our function in Python, I used cdef, but for the function itself, I used cpdef

Also, notice we typed the I in the for loop and the function since it returns an int.

Now we have to compile our .pyx. In a separate file (mine is named setup.py), write the following code.

from distutils.core import setup
from Cython.Build import cythonizesetup(ext_modules = cythonize('The_Name_Of_Your_Pyx_Here.pyx'))

Finally, in terminal(make sure you are in the same folder), run the line

python setup.py build_ext --inplace

This should’ve compiled your pyx, and you should see a file of the same name with the extension .c instead of pyx

You can now import your c functions into local python files, given that you used cpdef, just by import’ name of your file’. IDEs tend to give me import errors even though they imported fine. You can also import python libraries into the pyx file, but in my experience, it performs the same as it would in Python.

Cython is a compiler for the Python programming language meant to optimize performance and form an extended Cython programming language. As an extension of Python, Cython is also a superset of the Python language, and it supports calling C functions and declaring C types on variables and class attributes. This makes it easy to wrap external C libraries, embed C into existing applications, or write C extensions for Python in syntax as easy as Python itself.

Cython is commonly used to create C modules that speed up Python code execution. This is important in complex applications where an interpreted language isn't efficient.

Install Cython

You can install Cython on Linux, BSD, Windows, or macOS using Python:

$ python -m pip install Cython

Once installed, it's ready to use.

Transform Python into C

A good way to start with Cython is with a simple "hello world" application. It's not the best demonstration of Cython's advantages, but it shows what happens when you're using Cython.

First, create this simple Python script in a file called hello.pyx (the .pyx extension isn't magical and it could technically be anything, but it's Cython's default extension):

print("hello world")

Next, create a Python setup script. A setup.py file is like Python's version of a makefile, and Cython can use it to process your Python code:

from setuptools import setup

from Cython.Build import cythonize


setup(

    ext_modules = cythonize("hello.pyx")

)

Finally, use Cython to transform your Python script into C code:

$ python setup.py build_ext --inplace

You can see the results in your project directory. Cython's cythonize module transforms hello.pyx into a hello.c file and a .so library. The C code is 2,648 lines, so it's quite a lot more text than the single line of hello.pyx source. The .so library is also over 2,000 times larger than its source (54,000 compared to 20 bytes). Then again, Python is required to run a single Python script, so there's a lot of code propping up that single-line hello.pyx file.

To use the C code version of your Python "hello world" script, open a Python prompt and import the new hello module you created:

>>> import hello

hello world

Integrate C code into Python

A good generic test of computational power is calculating prime numbers. A prime number is a positive number greater than 1 that produces a positive integer only when divided by 1 or itself. It's simple in theory, but as numbers get larger, the calculation requirements also increase. In pure Python, it can be done in under 10 lines of code:

import sys


number = int(sys.argv[1])

if not number <= 1:

    for i in range(2, number):

        if (number % i) == 0:

            print("Not prime")

            break

else:

    print("Integer must be greater than 1")

This script is silent upon success and returns a message if the number is not prime:

$ ./prime.py 3

$ ./prime.py 4

Not prime.

Converting this to Cython requires a little work, partly to make the code appropriate for use as a library and partly for performance.

Scripts and libraries

Many users learn Python as a scripting language: you tell Python the steps you want it to perform, and it does the work. As you learn more about Python (and open source programming in general), you learn that much of the most powerful code out there is in the libraries that other applications can harness. The less specific your code is, the more likely it can be repurposed by a programmer (you included) for other applications. It can be a little more work to decouple computation from workflow, but in the end, it's usually worth the effort.

In the case of this simple prime number calculator, converting it to Cython begins with a setup script:

from setuptools import setup

from Cython.Build import cythonize


setup(

    ext_modules = cythonize("prime.py")

)

Transform your script into C:

$ python setup.py build_ext --inplace

Everything appears to be working well so far, but when you attempt to import and use your new module, you get an error:

>>> import prime

Traceback (most recent call last):

  File "", line 1, in <module>

  File "prime.py", line 2, in init prime

    number = sys.argv[1]

IndexError: list index out of range

The problem is that a Python script expects to be run from a terminal, where arguments (in this case, an integer to test as a prime number) are common. You need to modify your script so that it can be used as a library instead.

Write a library

Libraries don't use system arguments and instead accept arguments from other code. Instead of using sys.argv to bring in user input, make your code a function that accepts an argument called number (or num or whatever variable name you prefer):

def calculate(number):

    if not number <= 1:

        for i in range(2, number):

            if (number % i) == 0:

                print("Not prime")

                break

    else:

        print("Integer must be greater than 1")

This admittedly makes your script somewhat difficult to test because when you run the code in Python, the calculate function is never executed. However, Python programmers have devised a common, if not intuitive, workaround for this problem. When the Python interpreter executes a Python script, there's a special variable called __name__ that gets set to __main__, but when it's imported as a module, __name__ is set to the module's name. By leveraging this, you can write a library that is both a Python module and a valid Python script:

import sys


def calculate(number):

    if not number <= 1:

        for i in range(2, number):

            if (number % i) == 0:

                print("Not prime")

                break

    else:

        print("Integer must be greater than 1")


if __name__ == "__main__":

    number = sys.argv[1]    

    calculate( int(number) )

Now you can run the code as a command:

$ python ./prime.py 4

Not a prime

And you can convert it to Cython for use as a module:

>>> import prime

>>> prime.calculate(4)

Not prime

C Python

Converting code from pure Python to C with Cython can be useful. This article demonstrates how to do that part, yet there are Cython features to help you optimize your code before conversion, options to analyze your code to find when Cython interacts with C, and much more. If you're using Python, but you're looking to enhance your code with C code or further your understanding of how libraries provide better extensibility than scripts, or if you're just curious about how Python and C can work together, then start experimenting with Cython.

Does Python compile down to C?

Does Cython convert Python to C?