笔记：python 调用 shell 和 C

python 调用 C ：

还是shell 获得linux 相关比较简单。

目前发现cmd好用。但是不适合很长的shell命令。只能写在脚本哩。。。[最好用的方法应该是？？？

pythhon 调用C 的时候，向C传递的参数=======发现直接传int不对。。。字符串接收是可以的。

C++ 编译为so 供 python调用，命令：

g++ perm.cpp -fPIC -shared -o perm.so

python

python 代码：

import sys
import os
import glob
import subprocess
import shutil
import traceback
import fcntl
import signal
import ConfigParser
import time

def get_files():
        global file
        cmd = ["sh", "./test.sh"]
        process = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE )
        out = process.communicate()
        if process.returncode == 0 and out[0].strip() != "NULL":
            """ print out
             for i in range(len(out)):
                print out[i].strip()"""
            number_i = out[0].strip()
            print number_i
            import ctypes
            so = ctypes.CDLL("./perm.so")
            ret = so.v_perm_v(number_i)
            print("the return value is:")
            print ret

def main(argv=None):
    """creates a parser for the command line arguments and runs the program for
       those arguments"""
    get_files()

if __name__ == "__main__":
    sys.exit(main())

~

ls /home/vivi | wc -l

shell:

ls /home/vivi | wc -l

C代码：

#include <stdio.h>
#include <stdlib.h>
#define  elemType  int

void arrySwap(elemType arr[], elemType a, elemType b)
{
    elemType temp;
    temp = arr[a];
    arr[a] = arr[b];
    arr[b] = temp;
}

int cnt = 0;
void perm(elemType arr[], int start, int end)
{
    if(start == end)
    {
        cnt++;
        printf("%d :/t",cnt);

        for(int i = 0; i <= end; i++)
            printf("%d ", arr[i]);

        printf("\n");
    }
    else
    {
        for(int i = start; i <= end; i++)
        {
            arrySwap(arr, start, i);
            perm(arr, start + 1, end);
            arrySwap(arr, start, i);
        }
    }
}
extern "C"
{
        int v_perm_v(char* len_c)
        {
           //printf("len_c = %s\n",len_c);
           int len = (int)(len_c[0] - '0');
           //printf("len = %d\n", len);
           if(len <= 0)
                return -1;
            int *arr = (int *)malloc(sizeof(int) * len);
            if(arr == NULL)
                return -1;
            for(int i = 0; i < len; i++)
            {
                arr[i] = i;
                //printf("%d ", arr[i]);
            }
            perm(arr, 0, len - 1);

            return 0;
        }
}