分组构造描述正则表达式的子表达式并捕获输入字符串的子字符串。下表列出了分组结构：
| 分组结构 | 描述 | 模式 | 匹配 |
|---|---|---|---|
( subexpression ) |
捕获匹配的子表达式，并将其分配为从零开始的序数 | (\w)\1 |
"ee"匹配"deep" |
(?< name >subexpression) |
将匹配的子表达式捕获到命名组中 | (?< double>\w)\k< double> |
"ee"匹配"deep" |
(?< name1 -name2 >subexpression) |
定义平衡组定义 | (((?'Open'\()[^\(\)]*)+((?'Close-Open'\))[^\(\)]*)+)*(?(Open)(?!))$ |
"((1-3)*(3-1))"匹配"3+2^((1-3)*(3-1))" |
(?: subexpression) |
定义非捕获组 | Write(?:Line)? |
"WriteLine" 匹配"Console.WriteLine()" |
(?imnsx-imnsx:subexpression) |
在子表达式中应用或禁用指定的选项 | A\d{2}(?i:\w+)\b |
"A12xl", "A12XL" 匹配 "A12xl A12XL a12xl" |
(?= subexpression) |
零宽正向前瞻断言 | \w+(?=\.) |
"is", "ran", 和 "out" 匹配 "He is. The dog ran. The sun is out." |
(?! subexpression) |
零宽度负向前瞻断言 | \b(?!un)\w+\b |
"sure", "used" 匹配 "unsure sure unity used" |
(?< =subexpression) |
零宽度正向后断言 | (?< =19)\d{2}\b |
"51", "03" 匹配 "1851 1999 1950 1905 2003" |
(?< ! subexpression) |
零宽度负向后断言 | (?< !19)\d{2}\b |
"ends", "ender" 匹配 "end sends endure lender" |
(?> subexpression) |
非追溯(或“贪懒”)子表达式 | [13579](?>A+B+) |
"1ABB", "3ABB" 和 "5AB" 匹配 "1ABB 3ABBC 5AB 5AC" |