首先要建立伺服器建立起socket，然後與本地的埠進行繫結，接著就開始接收客戶端的請求並建立與它的連線，接下來，客戶端傳送的訊息。

tcpserver.c程式碼：

int main()
{
    struct sockaddr_in server_sockaddr,client_sockaddr;
    int sin_size,recvbytes;
    int sockfd, client_fd;
    char buf[BUFFER_SIZE];

    /* 建立socket連線 */
    if((sockfd = socket(AF_INET,SOCK_STREAM,0
 
)) == -1)
    {
        perror("socket");
        exit(1);
    }

    printf("Socket id = %d\n",sockfd);

    /* 設定socket_in 結構體中相關的引數 */
    server_sockaddr.sin_family = AF_INET;               /* ipv4的協議 */
    server_sockaddr.sin_port = htons(PORT);             /* 設定埠 */
    server_sockaddr.sin_addr.s_addr = INADDR_ANY;       /* ip地址伺服器這邊的地址 */
 

    bzero(&(server_sockaddr.sin_zero),8);               /* 保持位數 */

    int i = 1;              /* 允許重複使用本地地址與套接字進行繫結 */
    setsockopt(sockfd,SOL_SOCKET,SO_REUSEADDR, &i,sizeof(i));

    /* 繫結函式bind（） */
    if(bind(sockfd,(struct sockaddr *)&server_sockaddr,sizeof(struct sockaddr))== -1)
    {
        perror("bind"
 
);
        exit(1);
    }

    printf("bind success!\n");

    /* 呼叫listen（）函式，建立未處理請求的佇列 */
    if( listen(sockfd, MAX_QUE_CONN_NM) == -1)
    {
        perror("listen");
        exit(1);
    }
    printf("Listening....\n");

    /* 呼叫accept（）function,waiting client connnectting */
    if((client_fd = accept(sockfd, (struct sockaddr *) & client_sockaddr,&sin_size)) == -1)
    {
        perror("accept");
        exit(1);
    }

    memset(buf,0,sizeof(buf));

    if((recvbytes = recv(client_fd,buf,BUFFER_SIZE,0)) == -1)
    {
        perror("recv");
        exit(1);
    }

    printf("Received a message :%s\n",buf);
    close(sockfd);
    exit(0);
}

客戶端的程式：

#include "myinclude.h"
int main(int argc, char *argv[])
{
    int sockfd,sendbytes;
    char buf[BUFFER_SIZE];
    struct hostent *host;
    struct sockaddr_in serv_adr;

    if(argc < 3)
    {
        fprintf(stderr,"USAGE:./client Hostname(or ipaddress)Text\n ");
        exit(1);
    }
/* address resolution function */
    if((host = gethostbyname(argv[1])) == NULL)
    {
        perror("gethostbyname");
        exit(1);
    }

    memset(buf,0,sizeof(buf));
    sprintf(buf,"%s",argv[2]);
/* create socket */
    if((sockfd = socket(AF_INET,SOCK_STREAM,0)) == -1)
    {
        perror("socket");
        exit(1);
    }
/* set up the structure-related parameters of sockaddr_in */
    serv_adr.sin_family = AF_INET;
    serv_adr.sin_port = htons(PORT);
    serv_adr.sin_addr = *((struct in_addr *)host->h_addr);
    bzero(&(serv_adr.sin_zero),8);
/* call connect function Initiate a connection to the server */
    if(connect(sockfd,(struct sockaddr *)&serv_adr,sizeof(struct sockaddr)) == -1)
    {
        perror("connect");  
        exit(1);
    }
/* send messages to server */
    if((sendbytes = send(sockfd,buf,strlen(buf),0))==-1)
    {
        perror("Send");
        exit(1);
    }

    close(sockfd);
    exit(0);
}