How to call C function in Python

Have you ever encountered a situation where you had to call a C function using python? This article will help you at a very basic level, and if you haven't come across this situation, you'll be happy to know how it's done.

First, let’s write a simple function in C and generate a shared library for that file. Assume the file name is function.c.

int myFunction(int num) 
{ 
    if (num == 0) 
  
        //如果number为0，则不执行任何操作。 
        return 0; 
    else
        // 如果number是2的幂，则返回1，否则返回0
          
    num & (num - 1) == 0 ? return 1 : return 0 
}

Compilation:

cc -fPIC -shared -o libfun.so function.c

Use the ctypes (external function interface) library to call C functions from Python

The above statement will generate a file called libfun .so shared library. Now, let's see how to use it in python. In python we have a library called ctypes. Using this library we can use C functions in python.

Assume the file name is function.py.

import ctypes 
NUM = 16      
# libfun loaded to the python file 
# using fun.myFunction(), 
# C function can be accessed 
# but type of argument is the problem. 
                         
fun = ctype.CDLL(libfun.so)   
# Now whenever argument  
# will be passed to the function                                                         
# ctypes will check it. 
            
fun.myFunction.argtypes(ctypes.c_int) 
  
# now we can call this  
# function using instant (fun) 
# returnValue is the value  
# return by function written in C  
# code 
returnVale = fun.myFunction(NUM)

This article is an introduction to the method of calling C functions in Python. I hope it will be helpful to friends in need!

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