C语言中的Socket programmimg,需要示例代码和教程

#include<stdio.h>
#include <stdlib.h>
#include<string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <netinet/in.h>

int main(int argc, char *argv[])
{
    int sockfd, new_sockfd;
    socklen_t clilen;
    char buffer[256];
    struct sockaddr_in serv_addr, cli_addr;
    int n;

    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    if (sockfd < 0) {
        perror("ERROR opening socket");
        exit(1);
    }

    bzero((char *) &serv_addr, sizeof(serv_addr));

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(12345);

    if (bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0) {
        perror("ERROR on binding");
        exit(1);
    }

    listen(sockfd, 5);
    clilen = sizeof(cli_addr);
    new_sockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);

    if (new_sockfd < 0) {
        perror("ERROR on accept");
        exit(1);
    }

    bzero(buffer, 256);
    n = read(new_sockfd, buffer, 255);

    if (n < 0) {
        perror("ERROR reading from socket");
        exit(1);
    }

    printf("Here is the message: %s\n", buffer);

    n = write(new_sockfd, "I got your message", 18);

    if (n < 0) {
        perror("ERROR writing to socket");
        exit(1);
    }

    close(new_sockfd);
    close(sockfd);

    return 0;
}

#include<stdio.h>
#include <stdlib.h>
#include<string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <netinet/in.h>

int main(int argc, char *argv[])
{
    int sockfd;
    struct sockaddr_in serv_addr;
    char buffer[256];
    int n;

    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    if (sockfd < 0) {
        perror("ERROR opening socket");
        exit(1);
    }

    bzero((char *) &serv_addr, sizeof(serv_addr));

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
    serv_addr.sin_port = htons(12345);

    if (connect(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0) {
        perror("ERROR connecting");
        exit(1);
    }

    printf("Please enter the message: ");
    bzero(buffer, 256);
    fgets(buffer, 255, stdin);

    n = write(sockfd, buffer, strlen(buffer));

    if (n < 0) {
        perror("ERROR writing to socket");
        exit(1);
    }

    bzero(buffer, 256);
    n = read(sockfd, buffer, 255);

    if (n < 0) {
        perror("ERROR reading from socket");
        exit(1);
    }

    printf("%s\n", buffer);

    close(sockfd);

    return 0;
}