linux socketのシンプルなアプリケーション-リターンサーバとクライアント

linuxの下でこれは最も経典のsocketで実現するケースであるべきで、unpの中で使う1つのケースで練習手を書いて、直接コードに行きます
server.cpp

#include
#include
#include
#include
#include
#include	//        
using namespace std;
#define ERROR_EXIT(msg) do{\
    perror(msg);\
    exit(EXIT_FAILURE);\
}while(0)
#define PORT 8080
#define BACKLOG 5
#define BSIZE 1024
int main(){
    int sockfd;
    sockfd=socket(AF_INET,SOCK_STREAM,0);
    if(sockfd==0)
        ERROR_EXIT("socket");
    struct sockaddr_in serveraddr;
    memset(&serveraddr, 0 ,sizeof(serveraddr));
    serveraddr.sin_port = htons(PORT);
    serveraddr.sin_addr.s_addr = INADDR_ANY;
    serveraddr.sin_family = AF_INET;
    if(::bind(sockfd, (struct sockaddr *)&serveraddr, sizeof(serveraddr))<0)
        ERROR_EXIT("bind");
    if(listen(sockfd, BACKLOG)<0)
        ERROR_EXIT("listen");
    
    socklen_t len;
    sockaddr_in clientaddr;
    len=sizeof(clientaddr);
    int conn=accept(sockfd, (struct sockaddr *)&clientaddr, &len);
    if(conn<0)
        ERROR_EXIT("accept");
    
    char recvbuf[BSIZE];
    while(1){
        int nread=read(conn, recvbuf, sizeof(recvbuf));
        if(nread==0)
            break;
        else
            printf("Receive:%s
",recvbuf);
        write(conn, recvbuf, sizeof(recvbuf));
    }
    close(conn);
    close(sockfd);
    return 0;
}

client.cpp

#include
#include
#include
#include
#include
#include
using namespace std;
#define ERROR_EXIT(msg) do{\
    perror(msg);\
    exit(EXIT_FAILURE);\
}while(0)
#define PORT 8080
#define BSIZE 1024
int main(){
    int clientfd=socket(AF_INET, SOCK_STREAM, 0);
    if(clientfd<0)
        ERROR_EXIT("socket");
    struct sockaddr_in serveraddr;
    memset(&serveraddr, 0, sizeof(serveraddr));
    serveraddr.sin_port = htons(PORT);
    serveraddr.sin_addr.s_addr = inet_addr("127.0.0.1");
    serveraddr.sin_family = AF_INET;

    if(connect(clientfd, (struct sockaddr *)&serveraddr, sizeof(serveraddr)))
        ERROR_EXIT("connect");
    char recvbuf[BSIZE];
    char sendbuf[BSIZE];
    while(1){
        scanf("%s",sendbuf);
        write(clientfd, sendbuf, sizeof(sendbuf));
        read(clientfd, recvbuf, sizeof(recvbuf));
        printf("%s
",recvbuf);
    }
    close(clientfd);
    return 0;
}

どこにもわからない