client_thread.c#include <stdio.h>#include <sys/types.h>#include <sys/socket.h>#include <sys/un.h>#include <netdb.h>#include <unistd.h>int main(int argc,char *argv[]){    int connect_fd;    int ret;    char snd_buf[1024];    int i;    int port;    int len;    static struct sockaddr_in srv_addr;    //客户端运行需要给出具体的连接地址和端口     if(argc!=3)    {        printf("Usage: %s server_ip_address port\n",argv[0]);        return 1;    }    //获得输入的端口    port=atoi(argv[2]);    //创建套节字用于客户端的连接    connect_fd=socket(PF_INET,SOCK_STREAM,0);    if(connect_fd<0)    {        perror("cannot create communication socket");        return 1;    }    //填充关于服务器的套节字信息    memset(&srv_addr,0,sizeof(srv_addr));    srv_addr.sin_family=AF_INET;    srv_addr.sin_addr.s_addr=inet_addr(argv[1]);    srv_addr.sin_port=htons(port);    //连接指定的服务器     ret=connect(connect_fd,(struct sockaddr *)&srv_addr,sizeof(srv_addr));    if(ret==-1)    {        perror("cannot connect to the server");        close(connect_fd);        return 1;    }    memset(snd_buf,0,1024);    //用户输入信息后，程序将输入的信息通过套接字发送给服务器     //然后调用read函数从服务器中读取发送来的信息     //当输入“@”时，程序退出     while(1)    {        write(STDOUT_FILENO,"input message:",14);        len=read(STDIN_FILENO,snd_buf,1024);        if(len>0)            write(connect_fd,snd_buf,len);        len=read(connect_fd,snd_buf,len);        if(len>0)            printf("Message form server: %s\n",snd_buf);        if(snd_buf[0]==‘@‘)            break;    }    close(connect_fd);    return 0;}server_thread.c#include <stdio.h>#include <sys/types.h>#include <sys/socket.h>#include <sys/un.h>#include <errno.h>#include <unistd.h>#include <signal.h>#include <sys/wait.h>#include <netdb.h>#include <pthread.h>//线程执行函数负责读写void *thr_fn(void *arg){    int size,j;    char recv_buf[1024];    int *parg=(int *)arg;    int new_fd=*parg;    printf("new_fd=%d\n",new_fd);    while((size=read(new_fd,recv_buf,1024))>0)    {        if(recv_buf[0]==‘@‘)            break;        printf("Message from client(%d): %s\n",size,recv_buf);        for(j=0;j<size;j++)            recv_buf[j]=toupper(recv_buf[j]);        write(new_fd,recv_buf,size);    }    close(new_fd);    return 0;}int main(int argc,char *argv[]){    socklen_t clt_addr_len;    int listen_fd;    int com_fd;    int ret;    int i;    static char recv_buf[1024];    int len;    int port;    pthread_t tid;    struct sockaddr_in clt_addr;    struct sockaddr_in srv_addr;    //服务器端运行时要给出端口信息，该端口为监听端口     if(argc!=2)    {        printf("Usage:%s port\n",argv[0]);        return 1;    }    //获得输入的端口     port=atoi(argv[1]);    //创建套接字用于服务器的监听     listen_fd=socket(PF_INET,SOCK_STREAM,0);    if(listen_fd<0)    {        perror("cannot create listening socket");        return 1;    }    //填充关于服务器的套节字信息    memset(&srv_addr,0,sizeof(srv_addr));    srv_addr.sin_family=AF_INET;    srv_addr.sin_addr.s_addr=htonl(INADDR_ANY);    srv_addr.sin_port=htons(port);    //将服务器和套节字绑定    ret=bind(listen_fd,(struct sockaddr *)&srv_addr,sizeof(srv_addr));    if(ret==-1)    {        perror("cannot bind server socket");        close(listen_fd);        return 1;    }    //监听指定端口，连接5个客户端     ret=listen(listen_fd,5);    if(ret==-1)    {        perror("cannot listen the client connect request");        close(listen_fd);        return 1;    }    //对每个连接来的客户端创建一个线程，单独与其进行通信     //首先调用read函数读取客户端发送来的信息     //将其转换成大写后发送回客户端     //当输入“@”时，程序退出     while(1)    {        len=sizeof(clt_addr);        com_fd=accept(listen_fd,(struct sockaddr *)&clt_addr,&len);        if(com_fd<0)        {            if(errno==EINTR)            {                continue;            }            else            {                perror("cannot accept client connect request");                close(listen_fd);                return 1;            }        }        printf("com_fd=%d\n",com_fd);//打印建立连接的客户端产生的套节字        if((pthread_create(&tid,NULL,thr_fn,&com_fd))==-1)        {            perror("pthread_create error");            close(listen_fd);            close(com_fd);            return 1;        }    }    return 0;}

//打印线程 IDs#include <pthread.h>#include <stdlib.h>#include <stdio.h>#include <unistd.h>#include <string.h>pthread_t ntid;void printids(const char *s) {    pid_t pid;    pthread_t tid;    pid = getpid();    tid = pthread_self();    printf("%s pid %u tid %u (0x%x)\n", s, (unsigned int) pid,    (unsigned int) tid, (unsigned int) tid);}void *thr_fn(void *arg) {    printids("new thread: ");    return ((void *) 0);}int main(void) {    int err;    err = pthread_create(&ntid, NULL, thr_fn, NULL);    if (err != 0)        printf("can‘t create thread: %s\n", strerror(err));    printids("main thread:");    sleep(1);    exit(0);}