#ifndef _MAIN_H#define _MAIN_H#include <stdio.h>#include <stdlib.h>#include <sys/socket.h>#include <error.h>#include <netinet/in.h>#include <unistd.h>#include <string.h>#include <arpa/inet.h>#include <ctype.h>#include <signal.h>#include <pthread.h>typedef struct user{	char user_name[20];	int sockfd;	struct user *next;}node;int group(node *head,char *msg);int single(node *head,char *name,char *msg);int record(char *filename,char *msg);int regist(char *name,char *passwd);int login(char *name,char *passwd);int showuser(node *head,int socket);int insert(node *head,node *ptr);int del(node *head,int socket);int help(int socket);#endif