#include <sys/types.h>#include <sys/socket.h>#include <stdio.h>#include <netinet/in.h>#include <arpa/inet.h>#include <unistd.h>#include "err_exit.h"#include "socketfun.h"int main(int argc,char ** argv){	int connfd;	int n;	int result;	char buf[MAXBUFFSIZE];				/* 與服務建立連接 */	connfd=socket_connect(NULL,STRPARALLELPORT);	if(argc==1){		strcpy(buf,"Hello World!");		write(connfd,buf,strlen(buf));	}else{		write(connfd,argv[1],strlen(argv[1]));	}	n=read(connfd,buf,sizeof(buf));	buf[n]=0;		/* 終止符 */	printf("string from server=%s\n",buf);	close(connfd);	exit(0);}