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这可以用gethostbyaddr( )来完成.
和gethostbyname( )一样,它也返回一个struct hostent类型的指针.
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,
意味着可以安全地重入.
#include
#include
#include
#include
main(int argc, const char **argv)
{
u_long addr;
struct hostent *hp;
char **p;
if (argc != 2) {
printf("用法: %s IP地址 ", argv[0]);
exit (1);
}
if ((int)(addr = inet_addr(argv[1])) == -1) {
printf("错误的IP地址. ");
exit (2);
}
hp = gethostbyaddr((char *)&addr, sizeof (addr), AF_INET);
if (hp == NULL) {
printf("Host information about %s not found. ", argv[1]);
exit (3);
}
printf("Official name: %s ",hp->h_name); //正式域名
printf("IP Addr: ");
for (p = hp->h_addr_list; *p ; p++) //循环显示所有IP
printf(" %s ", inet_ntoa(*p));
printf("Aliases: ");
for (p = hp->h_aliases; *p ; p++) //循环显示所有别名
printf(" %s ", *p);
}
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