Abstract
同學問我的小問題，還蠻有趣的，就順便寫寫看。
Introduction
使用環境：Visual C++ 9.0 / Visual Studio 2008
get_c_class_ip_host_id.c / C
1 /*
2 (C) OOMusou 2008 http://oomusou.cnblogs.com
3
4 Filename : get_c_class_ip_host_id.c
5 Compiler : Visual C++ 9.0 / Visual Studio 2008
6 Description : Demo how to get host id of C class IP.
7 Release : 07/30/2008 1.0
8 */
9 #include <stdio.h>
10 #include <string.h>
11
12 void get_hostid(char *s, char *t) {
13 char *u = strrchr(s, '.') + 1;
14 while(*t++=*u++);
15 }
16
17 int main() {
18 char s[] = "140.113.23.145";
19 char t[4];
20 get_hostid(s,t);
21 printf("%s", t);
22 }
2 (C) OOMusou 2008 http://oomusou.cnblogs.com
3
4 Filename : get_c_class_ip_host_id.c
5 Compiler : Visual C++ 9.0 / Visual Studio 2008
6 Description : Demo how to get host id of C class IP.
7 Release : 07/30/2008 1.0
8 */
9 #include <stdio.h>
10 #include <string.h>
11
12 void get_hostid(char *s, char *t) {
13 char *u = strrchr(s, '.') + 1;
14 while(*t++=*u++);
15 }
16
17 int main() {
18 char s[] = "140.113.23.145";
19 char t[4];
20 get_hostid(s,t);
21 printf("%s", t);
22 }
執行結果
145