為了能夠更好地理解如何在C#環境中使用Regex，我寫出一些對你來說可能有用的Regex，這些運算式在其他的環境中都被使用過，希望能夠對你有所協助。
羅馬數字
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);
交換前二個單詞
string t2 = "the quick brown fox";
string p2 = @"(\S+)(\s+)(\S+)";
Regex x2 = new Regex(p2);
string r2 = x2.Replace(t2, "$3$2$1", 1);
關健字=值
string t3 = "myval = 3";
string p3 = @"(\w+)\s*=\s*(.*)\s*$";
Match m3 = Regex.Match(t3, p3);
實現每行80個字元
string t4 = "********************"
+ "******************************"
+ "******************************";
string p4 = ".{80,}";
Match m4 = Regex.Match(t4, p4);
月/日/年 小時:分:秒的時間格式
string t5 = "01/01/01 16:10:01";
string p5 = @"(\d+)/(\d+)/(\d+) (\d+):(\d+):(\d+)";
Match m5 = Regex.Match(t5, p5);
改變目錄（僅適用於Windows平台）
string t6 = @"C:\Documents and Settings\user1\Desktop\";
string r6 = Regex.Replace(t6,@"\\user1\\", @"\\user2\\");
擴充16位轉義符
string t7 = "%41"; // capital A
string p7 = "%([0-9A-Fa-f][0-9A-Fa-f])";
string r7 = Regex.Replace(t7, p7, HexConvert);
刪除C語言中的注釋（有待完善）
string t8 = @"
/*
* 傳統風格的注釋
*/
";
string p8 = @"
/\* # 匹配注釋開始的定界符
.*? # 匹配注釋
\*/ # 匹配注釋結束定界符
";
string r8 = Regex.Replace(t8, p8, "", "xs");
刪除字串中開始和結束處的空格
string t9a = " leading";
string p9a = @"^\s+";
string r9a = Regex.Replace(t9a, p9a, "");
string t9b = "trailing ";
string p9b = @"\s+$";
string r9b = Regex.Replace(t9b, p9b, "");
在字元\後添加字元n，使之成為真正的新行
string t10 = @"\ntest\n";
string r10 = Regex.Replace(t10, @"\\n", "\n");
轉換IP地址
string t11 = "55.54.53.52";
string p11 = "^" +
@"([01]?\d\d|2[0-4]\d|25[0-5])\." +
@"([01]?\d\d|2[0-4]\d|25[0-5])\." +
@"([01]?\d\d|2[0-4]\d|25[0-5])\." +
@"([01]?\d\d|2[0-4]\d|25[0-5])" +
"$";
Match m11 = Regex.Match(t11, p11);
刪除檔案名稱包含的路徑
string t12 = @"c:\file.txt";
string p12 = @"^.*\\";
string r12 = Regex.Replace(t12, p12, "");
聯結多行字串中的行
string t13 = @"this is
a split line";
string p13 = @"\s*\r?\n\s*";
string r13 = Regex.Replace(t13, p13, " ");
提取字串中的所有數字
string t14 = @"
test 1
test 2.3
test 47
";
string p14 = @"(\d+\.?\d*|\.\d+)";
MatchCollection mc14 = Regex.Matches(t14, p14);
找出所有的大寫字母
string t15 = "This IS a Test OF ALL Caps";
string p15 = @"(\b[^\Wa-z0-9_]+\b)";
MatchCollection mc15 = Regex.Matches(t15, p15);
找出小寫單詞
string t16 = "This is A Test of lowercase";
string p16 = @"(\b[^\WA-Z0-9_]+\b)";
MatchCollection mc16 = Regex.Matches(t16, p16);
找出第一個字母為大寫的單詞
string t17 = "This is A Test of Initial Caps";
string p17 = @"(\b[^\Wa-z0-9_][^\WA-Z0-9_]*\b)";
MatchCollection mc17 = Regex.Matches(t17, p17);
找出簡單的HTML語言中的連結
string t18 = @"
<html>
<a href=""first.htm"">first tag text</a>
<a href=""next.htm"">next tag text</a>
</html>
";
string p18 = @"<A[^>]*?HREF\s*=\s*[""']?" + @"([^'"" >]+?)[ '""]?>";
MatchCollection mc18 = Regex.Matches(t18, p18, "si");
