代码实现

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

int main(int argc, char *argv[])
{
	struct sockaddr_in   addr;
	struct hostent   *he;
	char    **alias;
	
	if(argc < 2)
	{
		printf("Usage: %s name | IP", argv[0]);
		exit(-1);
	}
	argv++;
	for( ; *argv != NULL; argv++)
	{
	/*·´ÏòÓòÃû½âÎöº¯Êýgethostbyaddr
	* ½«IP½âÎöΪÖ÷»úÃû
		* ÐèÒªÏȵôÓÃinet_aton»òinet_pton*/
		if(inet_aton(*argv, &addr.sin_addr)!=0)
		{
			he = gethostbyaddr((char *)&addr, sizeof(addr), AF_INET);
			printf("address information of IP %s: \n", *argv);
		}
		
		/*ÓòÃû½âÎöº¯Êýgethostbyname*/
		else
		{
			he = gethostbyname(*argv);
			printf("address information of host %s: \n", *argv);
		}
		if(he == NULL)
		{
			printf("no address information of %s\n", *argv);
			continue;
		}
		
		printf("Official host name: %s\n", he->h_name);
		printf("name aliases:");
		for(alias = he->h_aliases; *alias != NULL; alias++)
		{
			printf("%s    ", *alias);
		}
		printf("\nIP address: ");
		for(alias = he->h_addr_list; *alias != NULL; alias++)
		{
			printf("%s\n", inet_ntoa( *(struct in_addr *)(*alias)));
		}
	}
}

运行示例