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<td width="68%" background="DDl_back2.jpg" height="44"><big><big><font face="黑体"><p align="center"> ● UNIX网络编程 (BM: clown) </font></big></big></td></tr>
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<tr><td width="100%" colspan="2" height="100" align="center" valign="top"><br><p align="center">[<a href="index.htm">回到开始</a>][<a href="16.htm">上一层</a>][<a href="32.htm">下一篇</a>]
<hr><p align="left"><small>发信人: Happy (欢乐幸福人), 信区: Socket <br>
标 题: 如何在程序中将IP转换为域名 <br>
发信站: 华南网木棉站 (Tue Aug 11 18:48:12 1998), 转信 <br>
<br>
这可以用gethostbyaddr( )来完成. <br>
和gethostbyname( )一样,它也返回一个struct hostent类型的指针. <br>
在多线程环境下也有个替代函数gethostbyaddr_r( ).下划线后的r代表reentrant, <br>
意味着可以安全地重入. <br>
<br>
#include <stdio.h> <br>
#include <sys/types.h> <br>
#include <netdb.h> <br>
#include <sys/socket.h> <br>
<br>
main(int argc, const char **argv) <br>
{ <br>
u_long addr; <br>
struct hostent *hp; <br>
char **p; <br>
<br>
if (argc != 2) { <br>
printf("用法: %s IP地址\n", argv[0]); <br>
exit (1); <br>
} <br>
<br>
if ((int)(addr = inet_addr(argv[1])) == -1) { <br>
printf("错误的IP地址.\n"); <br>
exit (2); <br>
} <br>
<br>
hp = gethostbyaddr((char *)&addr, sizeof (addr), AF_INET); <br>
if (hp == NULL) { <br>
printf("Host information about %s not found.\n", argv[1]); <br>
exit (3); <br>
} <br>
printf("Official name: %s\n",hp->h_name); //正式域名 <br>
printf("IP Addr:\n"); <br>
for (p = hp->h_addr_list; *p ; p++) //循环显示所有IP <br>
printf(" %s\n", inet_ntoa(*p)); <br>
printf("Aliases:\n"); <br>
for (p = hp->h_aliases; *p ; p++) //循环显示所有别名 <br>
printf(" %s\n", *p); <br>
<br>
} <br>
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