{"id":1907,"date":"2023-06-01T08:40:43","date_gmt":"2023-06-01T01:40:43","guid":{"rendered":"https:\/\/csharptutorial.net\/?page_id=1907"},"modified":"2023-06-01T08:51:04","modified_gmt":"2023-06-01T01:51:04","slug":"regex-word-boundary","status":"publish","type":"page","link":"https:\/\/www.csharptutorial.net\/csharp-regular-expression\/regex-word-boundary\/","title":{"rendered":"Regex Word Boundary"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you will learn about word boundaries in regular expressions to match a position between a word character and a non-word character.<\/p>\n\n\n\n

Introduction to Regex word boundary<\/h2>\n\n\n\n

A word boundary defines a position that denotes the boundary between a word character and a non-word character.<\/p>\n\n\n\n

The following defines three positions in a string that are word boundaries:<\/p>\n\n\n\n

    \n
  1. At the start of the string, if the first character is a word character. (criterion #1)<\/li>\n\n\n\n
  2. At the end of the string, if the last character is a word character. (criterion #2)<\/li>\n\n\n\n
  3. Between a word character and a non-word character. (criterion #3)<\/li>\n<\/ol>\n\n\n\n

    For example, the word boundary positions in the string “C# 11” are as follows:<\/p>\n\n\n\n

      \n
    • Before the letter “C” (criterion #1).<\/li>\n\n\n\n
    • After the “#” symbol (criterion #3).<\/li>\n\n\n\n
    • After the space character between “C#” and “11”. (criterion #3)<\/li>\n\n\n\n
    • After the last character “1” (criterion #2).<\/li>\n<\/ul>\n\n\n\n

      Regular expressions use \\b<\/code> metacharacter to denote a word boundary. The \\b<\/code> metacharacter matches a word boundary in a string and does not match any actual character.<\/p>\n\n\n\n

      For example, the following pattern uses the \\b<\/code> word boundary to match the whole word in a string:<\/p>\n\n\n

      \\bword\\b<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
      The following example finds the matches that contain the word sea<\/code>:<\/p>\n\n\n
      using<\/span> System.Text.RegularExpressions;\nusing<\/span> static<\/span> System.Console;\n\n\nvar<\/span> text = \"She loves the sea and seaside\"<\/span>;\nvar<\/span> pattern = \"sea\"<\/span>;\n\nvar<\/span> matches = Regex.Matches(text, pattern);\nforeach<\/span> (var<\/span> match in<\/span> matches)\n{\n    WriteLine(match);\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
      It returns both sea<\/code> and seaside<\/code>. <\/p>\n\n\n\n
      To match the whole word sea<\/code>, you can use the word boundary \\b<\/code> like this:<\/p>\n\n\n
      using<\/span> System.Text.RegularExpressions;\nusing<\/span> static<\/span> System.Console;\n\n\nvar<\/span> text = \"She loves the sea and seaside\"<\/span>;\nvar<\/span> pattern = @\"\\bsea\\b\"<\/span>;\n\nvar<\/span> matches = Regex.Matches(text, pattern);\nforeach<\/span> (var<\/span> match in<\/span> matches)\n{\n    WriteLine(match);\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
      Output:<\/p>\n\n\n
      sea<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
      Now, it returns one match instead of two.<\/p>\n\n\n\n
      Summary<\/h2>\n\n\n\n
        \n
      • Use \\b<\/code> metacharacter to match a word boundary in a string.<\/li>\n\n\n\n
      • Use \\bword\\b<\/code> to match the whole word.<\/li>\n<\/ul>\n
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