linux 域名转ip

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

int main(int argc, char **argv)
{
if (argc != 2) {
fprintf(stderr, "Usage: %s hostname\n",
argv[1]);
exit(1);   
}

struct hostent *answer;
int i;
char ipstr[16];

answer = gethostbyname(argv[1]);
if (answer == NULL) {
herror("gethostbyname"); //由gethostbyname自带的错误处理函数
exit(1);
}

for (i = 0; (answer->h_addr_list)[i] != NULL; i++) {
inet_ntop(AF_INET, (answer->h_addr_list)[i], ipstr, 16);
printf("%s\n", ipstr);
printf("officail name : %s\n", answer->h_name);
}
exit(0);
}

 

-----------------------------------

#include <stdio.h>

#include <stdlib.h>

#include <errno.h>

#include <netdb.h>

#include <sys/types.h>

#include <netinet/in.h>

int main(int argc, char *argv[])

{

 struct hostent *h;

 char hostname[40];

 printf("请输入域名/n");

 scanf("%s",hostname);

 getchar();

 if((h=gethostbyname(hostname))==NULL)

 {

     fprintf(stderr,"不能得到IP/n");

     exit(1);

 }

 printf("HostName :%s/n",h->h_name);

 printf("IP Address :%s/n",inet_ntoa(*((struct in_addr *)h->h_addr)));

  return EXIT_SUCCESS;

}

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gethostbyname存在内存泄露。。建议用getaddrinfo.............2013-8-21