{"id":1961,"date":"2023-06-02T14:05:11","date_gmt":"2023-06-02T07:05:11","guid":{"rendered":"https:\/\/csharptutorial.net\/?page_id=1961"},"modified":"2023-06-02T14:05:13","modified_gmt":"2023-06-02T07:05:13","slug":"regex-non-capturing-group","status":"publish","type":"page","link":"https:\/\/www.csharptutorial.net\/csharp-regular-expression\/regex-non-capturing-group\/","title":{"rendered":"Regex Non-capturing Group"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you will learn about regex non-capturing groups and how to use them to avoid unnecessary overhead.<\/p>\n\n\n\n

Introduction to the Regex Non-capturing group<\/h2>\n\n\n\n

A capturing group<\/a> matches a pattern and stores a match result in matching groups. To create a capturing group, you place a pattern inside the parentheses ()<\/code> like this:<\/p>\n\n\n

(P)<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
In this syntax, the regex engine matches the pattern P<\/code> and stores the match result inside groups, which you can access via the Groups<\/code> property of the Match<\/code> object.<\/p>\n\n\n\n
In some situations, you want to create a group but you don’t want to capture it match result. To do that, you use a non-capturing group with the following syntax:<\/p>\n\n\n
(?:P)<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
When you use a non-capturing group, the regex engine matches the pattern P<\/code> but doesn’t store the match result in Groups<\/code>.<\/p>\n\n\n\n
Non-capturing groups also help you to write regular expressions that avoid unnecessary capture group overhead.<\/p>\n\n\n\n
Regex Non-capturing group example<\/h2>\n\n\n\n
The following example uses a non-capturing group to match a color code in the format \"#RRGGBB<\/code>\"<\/code> or \"0xRRGGBB<\/code>\"<\/code>:<\/p>\n\n\n
using<\/span> System.Text.RegularExpressions;\nusing<\/span> static<\/span> System.Console;\n\n\nvar<\/span> text = \"My favorite color is #00FF00.\"<\/span>;\nvar<\/span> pattern = @\"(?:#|0x)([A-Fa-f0-9]{6})\"<\/span>;\n\nvar<\/span> match = Regex.Match(text, pattern);\n\nif<\/span> (match.Success)\n{\n\n    WriteLine($\"Your favorite color code is {match.Groups[1<\/span>].Value}<\/span>\"<\/span>);\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
Your favorite color code is<\/span> 00F<\/span>F00<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
In the regular expression pattern (?:#|0x)([A-Fa-f0-9]{6})<\/code>:<\/p>\n\n\n\n
    \n
  • The non-capturing group (?:#|0x)<\/code> matches either the “#<\/code>” symbol or the “0x<\/code>” prefix.<\/li>\n\n\n\n
  • The capturing group ([A-Fa-f0-9]{6})<\/code> captures the actual color code.<\/li>\n<\/ul>\n\n\n\n
    Summary<\/h2>\n\n\n\n
      \n
    • Use non-capturing groups to group patterns together without capturing the matched substrings.<\/li>\n<\/ul>\n
      \n\t
      \n\t\t
      Was this tutorial helpful ?<\/div>\n\t\t
      \n\t\t\t\n\t\t\t\t\n\t\t\t\t\t<\/path>\n\t\t\t\t<\/svg>\n\t\t\t\t Yes <\/span>\n\t\t\t<\/button>\n\n\t\t\t\n\t\t\t\t\n\t\t\t\t\t<\/path>\n\t\t\t\t<\/svg>\n\t\t\t\t No <\/span>\n\t\t\t<\/button>\n\t\t<\/div>\n\t<\/header>\n\n\t
      \n\t\t
      \n\t\t\t
      <\/div>\n\t\t\t\n\t\t\t
Non-capturing groups are useful when you want to create a group and apply quantifiers<\/a>, alternations<\/a>, or other operations to a group of patterns but you don’t want to capture them. <\/p>\n\n\n\n