/*---------------------------------------------------------------------------------------------- 
ÆÄÀϸí : addr_conv.c 
±â ´É : ÁÖ¼Òº¯È¯ ÇÁ·Î±×·¥ 
ÄÄÆÄÀÏ : cc -o addr_conv addr_conv.c -lsocket -lnsl 
½ÇÇ࿹ : addr_conv vcn.kangwon.ac.kr 203.252.65.3 
----------------------------------------------------------------------------------------------*/ 
#include <netdb.h> 
#include <stdio.h> 
#include <string.h> 
#include <sys/types.h> 
#include <sys/socket.h> 
#include <netinet/in.h> 
#include <arpa/inet.h> 
int main(int argc, char *argv[]) { 
struct hostent *ptr_he;/* È£½ºÆ®ÀÇ Á¤º¸¸¦ ÀúÀåÇÏ´Â ±¸Á¶Ã¼ */ 
struct in_addr in;	/* ÀÎÅÍ³Ý ÁÖ¼Ò¸¦ ÀúÀåÇÏ´Â ±¸Á¶Ã¼ */ 
char *hname;	/* È£½ºÆ® À̸§ */ 
char *haddr;	/* dotted decimal IP ¹®ÀÚ¿­ */ 

if(argc != 3) { 
printf("Usage : %s hostname IP_address\n", argv[0]); 
return -1; 
} 
hname = argv[1]; 
haddr = argv[2]; 

/* È£½ºÆ® µµ¸ÞÀÎ ³×ÀÓÀ¸·ÎºÎÅÍ È£½ºÆ® Á¤º¸ ±¸Çϱâ */ 
if((ptr_he = gethostbyname(hname))) { 
memcpy(&in.s_addr,ptr_he->h_addr_list[0], sizeof(in.s_addr)); 
printf("%s\'s binary ip address (hexa) : 0x%x\n", hname, in.s_addr); 

/* IP ÁÖ¼Ò¸¦ dotted decimal ÇüÅÂÀÇ IP·Î º¯È¯ */ 
printf("%s\'s dotted decimal IP address : %s\n", hname, inet_ntoa(in)); 
} else { 
printf("gethostbyname error.\n"); 
} 

/* ÀÔ·ÂµÈ dotted decimal IP ÁÖ¼Ò¿¡¼­ binary IP ÁÖ¼Ò ±¸Çϱâ */ 
if((in.s_addr = inet_addr(haddr)) > 0) { 
ptr_he = gethostbyaddr((char *)&(in.s_addr), sizeof(in.s_addr), AF_INET); 
printf("%s\'s binary IP address (hexa) : 0x%x\n", haddr, in.s_addr); 
printf("%s\'s hostname : %s\n", haddr, ptr_he->h_name); 
} else { 
printf("inet_addr error.\n"); 
} 
}