c - socket编程中客户端如何同时读写

Question

我正在学习套接字和编程，我遇到了为一个简单的客户端编写的这段代码

#include<stdio.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<arpa/inet.h>
#include<netinet/in.h>
#include<string.h>
int main(int argc, char **argv)
{
    int len;
    int sockfd, n;
    struct sockaddr_in servaddr, cliaddr;
    char str[1000];
    char buff[1024];
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if(sockfd < 0)
        perror("Cannot create socket!\n");
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = inet_addr(argv[1]);
    servaddr.sin_port = htons(80);
    connect(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr));
    printf("Enter the message: ");
    scanf("%s", buff);
    n = write(sockfd, buff, sizeof(buff));
    n = read(sockfd, buff, sizeof(buff));
    printf("Response: %s\n", buff);
    close(sockfd);
    return 0;
}

根据我的解释，我猜客户端在套接字中写入一条消息以发送到服务器，并在下一行读取响应。但这怎么可能呢？它如何确认在发送消息后立即收到响应。不是要等到确认了吗？

标签： csocketsnetwork-programmingclient-server