罗马数字
string p1 = "^m*(d?c{0,3}|c[dm])" + "(l?x{0,3}|x[lc])(v?i{0,3}|i[vx])$";
string t1 = "vii";
Match m1 = Regex.Match(t1, p1);
交换前二个单词
string t2 = "the quick brown fox";
string p2 = @"(S+)(s+)(S+)";
Regex x2 = new Regex(p2);
string r2 = x2.Replace(t2, "$3$2$1", 1);
关健字=值
string t3 = "myval = 3";
string p3 = @"(w+)s*=s*(.*)s*$";
Match m3 = Regex.Match(t3, p3);
实现每行80个字符
string t4 = "********************"
+ "******************************"
+ "******************************";
string p4 = ".{80,}";
Match m4 = Regex.Match(t4, p4);
月/日/年 小时:分:秒的时间格式
string t5 = "01/01/01 16:10:01";
string p5 = @"(d+)/(d+)/(d+) (d+):(d+):(d+)";
Match m5 = Regex.Match(t5, p5);
改变目录（仅适用于Windows平台）
string t6 = @"C:Documents and Settingsuser1Desktop";
string r6 = Regex.Replace(t6,@"user1", @user2);
扩展16位转义符
string t7 = "%41"; // capital A
string p7 = "%([0-9A-Fa-f][0-9A-Fa-f])";
string r7 = Regex.Replace(t7, p7, HexConvert);
删除C语言中的注释（有待完善）
string t8 = @"
/*
* 传统风格的注释
*/
";
string p8 = @"
/* # 匹配注释开始的定界符
.*? # 匹配注释
*/ # 匹配注释结束定界符
";
string r8 = Regex.Replace(t8, p8, "", "xs");
删除字符串中开始和结束处的空格
string t9a = " leading";
string p9a = @"^s+";
string r9a = Regex.Replace(t9a, p9a, "");
string t9b = "trailing ";
string p9b = @"s+$";
string r9b = Regex.Replace(t9b, p9b, "");
在字符后添加字符n，使之成为真正的新行
string t10 = @"ntestn";
string r10 = Regex.Replace(t10, @"n", "n");
