python的pack unpack函数
转自:http://songpengfei.iteye.com/blog/1440637c语言在网络通信中经常会传输结构体数据,通常是二进制格式的,而python要想和c程序通信必须能够认识二进制的数据才行,不仅要认识而且还要能够解开c中的结构体数据,因为结构体通常会涉及到内存对齐的问题。
下面是一个例子,用python中的struct模块可以完成这个功能:
python写的服务器:
Python代码
[*]import socket, struct
[*]
[*]s = socket.socket()
[*]s.bind(('127.0.0.1', 8000))
[*]s.listen(1)
[*]
[*]try:
[*] while True:
[*] cli, addr = s.accept()
[*] data = cli.recv(100)
[*]
[*] print "recv %d bytes" % len(data)
[*] a, b, c = struct.unpack('i10sh', data)
[*] print a, b, c
[*]
[*] sdata = struct.pack('i10sh', 34, "abcdefghi\0", 65)
[*] cli.send(sdata)
[*]finally:
[*] s.close()
c写的客户端:
Java代码
[*]/* tcp_client.c */
[*]#include <stdio.h>
[*]#include <stdlib.h>
[*]#include <string.h>
[*]#include <sys/types.h>
[*]#include <sys/socket.h>
[*]#include <netinet/in.h>
[*]#include <arpa/inet.h>
[*]#include <unistd.h>
[*]
[*]typedef struct _data {
[*] int a;
[*] char b[10];
[*] short c;
[*]} Data;
[*]
[*]int main()
[*]{
[*] int client_fd;
[*] struct sockaddr_in server_addr;
[*]
[*] server_addr.sin_family = AF_INET;
[*] server_addr.sin_port = htons(8000);
[*] server_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
[*] bzero(&(server_addr.sin_zero), 8);
[*]
[*] client_fd = socket(AF_INET, SOCK_STREAM, 0);
[*]
[*] connect(client_fd, (struct sockaddr *)&server_addr, sizeof(struct sockaddr));
[*]
[*] Data d;
[*] memset(&d, 0, sizeof(d));
[*] d.a = 3;
[*] memcpy(&d.b, "hello", 5);
[*] d.c = 6;
[*] send(client_fd, &d, sizeof(d), 0);
[*]
[*] char buf[200];
[*] bzero(buf, 200);
[*] recv(client_fd, buf, sizeof(buf), 0);
[*]
[*] Data* p = (Data*)&buf;
[*] printf("%d %s %d\n", p->a, p->b, p->c);
[*]
[*] close(client_fd);
[*]
[*] return 0;
[*]}
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