{"id":1918,"date":"2023-06-01T13:40:28","date_gmt":"2023-06-01T06:40:28","guid":{"rendered":"https:\/\/csharptutorial.net\/?page_id=1918"},"modified":"2023-06-01T13:40:29","modified_gmt":"2023-06-01T06:40:29","slug":"regex-sets-and-ranges","status":"publish","type":"page","link":"https:\/\/www.csharptutorial.net\/csharp-regular-expression\/regex-sets-and-ranges\/","title":{"rendered":"Regex Sets and Ranges"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you will learn about regex sets and ranges to create patterns that match characters in a set of characters.<\/p>\n\n\n\n

Sets<\/h2>\n\n\n\n

When you place some characters inside square brackets []<\/code>, you create a set. For example, the [aeiou]<\/code> set matches any single lowercase vowel character.<\/p>\n\n\n\n

Typically, a set can be used with regular characters. Also, a set may contain multiple characters, each character within a set corresponds to only one character in the match. <\/p>\n\n\n\n

For example, licen[cs]e<\/code> pattern matches both licence<\/code> and license<\/code> as shown in the following example:<\/p>\n\n\n

using<\/span> System.Text.RegularExpressions;\nusing<\/span> static<\/span> System.Console;\n\nvar<\/span> text = \"A licence or license\"<\/span>;\nvar<\/span> pattern = @\"licen[cs]e\"<\/span>;\n\nvar<\/span> matches = Regex.Matches(text, pattern);\n\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
licence\nlicense<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Ranges<\/h2>\n\n\n\n
When a set has many characters e.g., from a to z, you don’t want to list them all in square brackets. Instead, you use a character range (-<\/code>) like this:<\/p>\n\n\n
[a-z<\/span>]<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
The [a-z]<\/code>1 is called a range that matches any character from a<\/code> to z<\/code>. Similarly, you can define a range of numbers from 0 to 9 as follows:<\/p>\n\n\n
[0-9<\/span>]<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
To define multiple ranges, you can place them next to each other inside the square brackets. For example:<\/p>\n\n\n
[a-z0-9<\/span>]<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
The range [a-z0-9]<\/code> matches any character that is from a<\/code> to z<\/code> and 0<\/code> to 9<\/code>.<\/p>\n\n\n\n
The following example uses the regex ranges to define a pattern that matches the time string in the format hh:mm<\/code>:<\/p>\n\n\n
using<\/span> System.Text.RegularExpressions;\nusing<\/span> static<\/span> System.Console;\n\n\nvar<\/span> text = \"12:30 15:60\"<\/span>;\nvar<\/span> pattern = @\"\\b[0-2][0-9]:[0-5][0-9]\\b\"<\/span>;\n\nvar<\/span> matches = Regex.Matches(text, pattern);\n\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
12<\/span>:30<\/span><\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
The pattern <\/p>\n\n\n\n
This pattern \\b[0-2][0-9]:[0-5][0-9]\\b<\/code> matches the time format hh:mm<\/code>, where the hour can be in the range of 00 to 23 and the minute can be in the range of 00 to 59.<\/p>\n\n\n\n
Excluding sets and ranges<\/h2>\n\n\n\n
Regular expressions use the caret character ^<\/code> to negate a set or a range. For example, the range [^0-9]<\/code> matches any character excluding a digit, which is equivalent to the \\D<\/code> character class<\/a>.<\/p>\n\n\n\n
It’s important to notice that when you use ^<\/code> inside a square bracket, it negates a set or a range. But if you use outside of a bracket, it is an anchor character that matches at the beginning of the string.<\/p>\n\n\n\n
Summary<\/h2>\n\n\n\n
    \n
  • Use square brackets []<\/code> to define a set or a range.<\/li>\n\n\n\n
  • Use the caret ^<\/code> inside the square bracket []<\/code> to negate a set or a range [^...]<\/code>.<\/li>\n<\/ul>\n
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