正则表达式

主要要素

字符

[a-zA-Z] 即 \w
[0-9] 即 \d
[^0-9] 即 \D
\s 即 空白
\S 即 非空白
. 通配符

次数

* 即 {0,}
+ 即 {1,}
? 即 {0,1}

*? +? ?? 懒惰匹配，尽量匹配少

| 或
() 组合

位置限定

^ 首
$ 尾
\b 单词边界
\B 非单词边界

(?<a>xxxx)(yyyy)

替换时：
${a} => $1 => xxxx
$2 => yyyy

(?i:xxxxx)

忽略大小写

Regex

命名空间：using System.Text.RegularExpressions;

Regex.IsMatch | Match | Matches | Replace(s,r)
Match.Groups | Value | Result

using System;
using System.Text.RegularExpressions;
class Test
{
    static void  Main()
    {
        /*示例*/
        string pattern = @"^[\. a-zA-z]+ (?<name>\w+), [a-zA-z]+, x(?<ext>\d+)$";
        string [] sa =
        {
            "Dr. David Jones, Ophthalmology, x2441",
            "Ms. Cindy Harriman, Registry, x6231",
            "Mr. Chester Addams, Mortuary, x1667",
            "Dr. Hawkeye Pierce, Surgery, x0986",
        };
  
        Regex rx = new Regex( pattern );
  
        foreach ( string s in sa )
        {
            Match m= rx.Match(s);
            if( m.Success )
                Console.Write(m.Result("${ext},  ${name}, $1"));
            Console.WriteLine( "\t" +
                rx.Replace( s, "姓：${name}, 分机号：${ext}" ));
        }
		
        /*示例*/
        string pattern = "[Bbw]ill";
        string s = "My friend Bill will pay the bill";
  
        if( Regex.IsMatch( s, pattern ) )
            Console.WriteLine( s+ "与" + pattern +"相匹配" );
          
        Regex  rx = new Regex( pattern );
          
        MatchCollection mc = rx.Matches(s);
        Console.WriteLine("有{0}次匹配", mc.Count);
        foreach ( Match mt in mc )
        {
            Console.WriteLine( mt );
        }   
  
        Match m = rx.Match(s);
        while ( m.Success )
        {
            Console.WriteLine("在位置 {0} 有匹配'{1}'", 
                m.Index, m.Value);
            m = rx.Match(s, m.Index+ m.Length);
        }
  
        for (m = rx.Match(s); m.Success; m = m.NextMatch()) 
        {
            Console.WriteLine("在位置 {0} 有匹配'{1}'", 
                m.Index, m.Value);
        }
    }
}