1.2 一个简单的时间获取客户程序

#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);
}