使用python调用c程序

问题

请编写一段Python代码，使其能调用C程序。

思路

这是一道课后作业，在题目里并没有说明怎么算用Python调用C程序，所以我考虑了以下两点：

• 使用Python调用C代码生成的可执行文件（windows下是exe文件）
• 使用Python调用C代码生成的共享库（windows下是dll文件）

实验环境

windows11、Python3.9、pycharm

主要用到的包

ctypes、subprocess、os

代码实现

此代码包含的内容：

• 使用python代码调用c可执行文件（exe）
• 使用python代码调用c共享库（dll）
• 使用python代码创建并编译c代码的过程

import os
import ctypes
import subprocess


def create_c_file(file_name):
    """
    Create a C file containing code to calculate the GCD of two integers.

    Args:
        file_name (str): The name of the C file to be created.
    """
    with open(file_name, 'w') as f:
        f.write('''
#include <stdio.h>
#include <stdlib.h>

/**
 * @brief 计算两个整数的最大公约数
 * 
 * @param a 第一个整数
 * @param b 第二个整数
 * @return int 两个整数的最大公约数
 */
int gcd(int a, int b) {
    while (b != 0) {
        int temp = b;
        b = a % b;
        a = temp;
    }
    return a;
}

/**
 * @brief 程序的主函数
 * 
 * @param argc 命令行参数的数量
 * @param argv 命令行参数的数组
 * @return int 返回0表示程序正常结束
 */
int main(int argc, char *argv[]) {
    if (argc != 3) {
        printf("Usage: %s num1 num2\\n", argv[0]);
        return 1;
    }

    int num1 = atoi(argv[1]);
    int num2 = atoi(argv[2]);
    int result = gcd(num1, num2);

    printf("GCD of %d and %d is %d\\n", num1, num2, result);
    return 0;
}
        ''')


def compile_c_file(file_name, output_name, shared=False):
    """
    Compile the C file into an executable or shared library.

    Args:
        file_name (str): The name of the C file to be compiled.
        output_name (str): The name of the output file (executable or shared library).
        shared (bool): Whether to compile as a shared library. Default is False.
    """
    args = ['gcc']
    if shared:
        args.extend(['-shared', '-fPIC'])
    args.extend(['-o', output_name, file_name])
    subprocess.check_call(args)


def load_gcd_library():
    """
    Load the compiled GCD shared library.

    Returns:
        ctypes.CDLL: The loaded GCD shared library.
    """
    gcd_library = ctypes.CDLL('./gcd.dll')
    gcd_library.gcd.argtypes = (ctypes.c_int, ctypes.c_int)
    gcd_library.gcd.restype = ctypes.c_int
    return gcd_library


def find_gcd(gcd_library, a, b):
    """
    Calculate the Greatest Common Divisor (GCD) of two integers using the GCD C library.

    Args:
        gcd_library (ctypes.CDLL): The loaded GCD shared library.
        a (int): The first integer.
        b (int): The second integer.

    Returns:
        int: The GCD of the two integers.
    """
    result = gcd_library.gcd(a, b)
    return result


def call_gcd_exe(file_name, num1, num2):
    """
    Call the GCD executable with two integers as command-line arguments.

    Args:
        file_name (str): The name of the executable file.
        num1 (int): The first integer.
        num2 (int): The second integer.
    Returns:
        int: The return code of the subprocess call. 0 indicates success.
    """
    return subprocess.call([file_name, str(num1), str(num2)])


def main():
    """
    The main function of the Python script.
    """
    c_file_name = 'gcd.c'
    shared_library_name = 'gcd.dll'
    executable_name = 'gcd.exe'
    # Create and compile the C file into a shared library and an executable
    create_c_file(c_file_name)
    compile_c_file(c_file_name, shared_library_name, shared=True)
    compile_c_file(c_file_name, executable_name)

    # Test the shared library
    gcd_library = load_gcd_library()
    num1 = 56
    num2 = 98
    result = find_gcd(gcd_library, num1, num2)
    print(f"Using shared library: GCD of {num1} and {num2} is {result}")

    # Test the executable
    ret_code = call_gcd_exe(executable_name, num1, num2)
    if ret_code != 0:
        print(f"An error occurred while calling the GCD executable. Return code: {ret_code}")


if __name__ == '__main__':
    main()

运行结果