关于socket写了无数遍了-优快云博客

本文展示了一个使用C语言实现的简单客户端程序示例，该程序能够连接到指定IP地址的daytime服务器，并读取服务器返回的时间信息。示例中包含了socket编程的基础知识，如创建套接字、设置服务器地址结构、连接服务器以及读取数据等。

#include    <stdio.h>
#include    <sys/socket.h>
#include    <netinet/in.h>
#define MAXLINE     4096
#define bzero(ptr,n)        memset(ptr, 0, n)
#define SA  struct sockaddr
int
main(int argc, char **argv)
{
    int                 sockfd, n;
    char                recvline[MAXLINE + 1];
    struct sockaddr_in  servaddr;

    if (argc != 2)
        printf("usage: a.out <IPaddress>");

    if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
        printf("socket error");

    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port   = htons(13);    /* daytime server */
    if (inet_pton(AF_INET, argv[1], &servaddr.sin_addr) <= 0)
        printf("inet_pton error for %s", argv[1]);

    if (connect(sockfd, (SA *) &servaddr, sizeof(servaddr)) < 0)
        printf("connect error");

    while ( (n = read(sockfd, recvline, MAXLINE)) > 0) {
        recvline[n] = 0;    /* null terminate */
        if (fputs(recvline, stdout) == EOF)
            printf("fputs error");
    }
    if (n < 0)
        printf("read error");

    exit(0);
}

unpv上的源码为


#include    "unp.h"

int
main(int argc, char **argv)
{
    int                 sockfd, n;
    char                recvline[MAXLINE + 1];
    struct sockaddr_in  servaddr;

    if (argc != 2)
        err_quit("usage: a.out <IPaddress>");

    if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
        err_sys("socket error");

    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port   = htons(13);    /* daytime server */
    if (inet_pton(AF_INET, argv[1], &servaddr.sin_addr) <= 0)
        err_quit("inet_pton error for %s", argv[1]);

    if (connect(sockfd, (SA *) &servaddr, sizeof(servaddr)) < 0)
        err_sys("connect error");

    while ( (n = read(sockfd, recvline, MAXLINE)) > 0) {
        recvline[n] = 0;    /* null terminate */
        if (fputs(recvline, stdout) == EOF)
            err_sys("fputs error");
    }
    if (n < 0)
        err_sys("read error");

    exit(0);
}