Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression

/
/
gm

Test String

Substitution

Processing...

Code Generator

Generated Code

using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @"(\(\)\n[[:space:]]{1,}\{)|(\(\)[[:space:]]{1,}\{)"; string substitution = @"()\n {\n clearScreen();"; string input = @"// feedback thread import java.util.*; class Main { static Scanner scan = new Scanner(System.in); static String deadEnd = ""dead end--morphing backwards!""; static String gettingCloser = ""You'r getting closer""; // call this method after each decision has been made public static void clearScreen() { Scanner scan = new Scanner(System.in); System.out.println(""Press enter to continue.""); String x = scan.nextLine(); System.out.print(""\033[H\033[2J""); System.out.flush(); } public static void decisionZero() { System.out.println(""Decision Point 0""); System.out.println(""Choose a direction Mr. Mouse""); String direction = scan.nextLine(); switch (direction.toLowerCase()) { case ""n"": System.out.println(""You chose north.""); System.out.println(deadEnd); decisionZero(); break; case ""s"": System.out.println(""You chose south.""); System.out.println(gettingCloser); decisionOne(); break; case ""e"": System.out.println(""You chose east.""); System.out.println(deadEnd); decisionZero(); break; case ""w"": System.out.println(""You chose west.""); System.out.println(deadEnd); decisionZero(); break; } } public static void decisionOne() { System.out.println(""Decision Point 1""); System.out.println(""Choose a direction Mr. Mouse""); String direction = scan.nextLine(); switch (direction.toLowerCase()) { case ""n"": System.out.println(""You chose north.""); System.out.println(deadEnd); decisionZero(); break; case ""s"": System.out.println(""You chose south.""); System.out.println(deadEnd); decisionZero(); break; case ""e"": System.out.println(""You chose east.""); System.out.println(deadEnd); decisionZero(); break; case ""w"": System.out.println(""You chose west.""); System.out.println(gettingCloser); decisionTwo(); break; } } public static void decisionTwo() { System.out.println(""Decision Point 2""); System.out.println(""Choose a direction Mr. Mouse""); String direction = scan.nextLine(); int rndDecion = (int)(Math.random()*2); switch (direction.toLowerCase()) { case ""n"": System.out.println(""You chose north.""); System.out.println(gettingCloser); decisionThree(); break; case ""s"": System.out.println(""You chose south.""); System.out.println(deadEnd); switch (rndDecion) { case 0: decisionZero(); case 1: decisionOne(); } break; case ""e"": System.out.println(""You chose east.""); System.out.println(deadEnd); switch (rndDecion) { case 0: decisionZero(); case 1: decisionOne(); } break; case ""w"": System.out.println(""You chose west.""); System.out.println(deadEnd); switch (rndDecion) { case 0: decisionZero(); case 1: decisionOne(); } break; } } public static void decisionThree() { System.out.println(""Decision Point 3""); System.out.println(""Choose a direction Mr. Mouse""); String direction = scan.nextLine(); int rndDecion = (int)(Math.random()*3); switch (direction.toLowerCase()) { case ""n"": System.out.println(""You chose north.""); System.out.println(gettingCloser); decisionFour(); break; case ""s"": System.out.println(""You chose south.""); System.out.println(deadEnd); switch (rndDecion) { case 0: decisionZero(); case 1: decisionOne(); case 2: decisionTwo(); } break; case ""e"": System.out.println(""You chose east.""); System.out.println(deadEnd); switch (rndDecion) { case 0: decisionZero(); case 1: decisionOne(); case 2: decisionTwo(); } break; case ""w"": System.out.println(""You chose west.""); System.out.println(deadEnd); switch (rndDecion) { case 0: decisionZero(); case 1: decisionOne(); case 2: decisionTwo(); } break; } } public static void decisionFour() { System.out.println(""Decision Point 4""); System.out.println(""Choose a direction Mr. Mouse""); String direction = scan.nextLine(); int rndDecion = (int)(Math.random()*4); switch (direction.toLowerCase()) { case ""n"": System.out.println(""You chose north.""); System.out.println(gettingCloser); decisionFive(); break; case ""s"": System.out.println(""You chose south.""); System.out.println(deadEnd); switch (rndDecion) { case 0: decisionZero(); case 1: decisionOne(); case 2: decisionTwo(); case 3: decisionThree(); } break; case ""e"": System.out.println(""You chose east.""); System.out.println(deadEnd); switch (rndDecion) { case 0: decisionZero(); case 1: decisionOne(); case 2: decisionTwo(); case 3: decisionThree(); } break; case ""w"": System.out.println(""You chose west.""); System.out.println(deadEnd); switch (rndDecion) { case 0: decisionZero(); case 1: decisionOne(); case 2: decisionTwo(); case 3: decisionThree(); } break; } } public static void decisionFive() { System.out.println(""Decision Point 5""); System.out.println(""Choose a direction Mr. Mouse""); String direction = scan.nextLine(); int rndDecion = (int)(Math.random()*5); switch (direction.toLowerCase()) { case ""n"": System.out.println(""You chose north.""); System.out.println(deadEnd); switch (rndDecion) { case 0: decisionZero(); case 1: decisionOne(); case 2: decisionTwo(); case 3: decisionThree(); case 4: decisionFour(); } break; case ""s"": System.out.println(""You chose south.""); System.out.println(deadEnd); switch (rndDecion) { case 0: decisionZero(); case 1: decisionOne(); case 2: decisionTwo(); case 3: decisionThree(); case 4: decisionFour(); } break; case ""e"": System.out.println(""You chose east.""); System.out.println(deadEnd); switch (rndDecion) { case 0: decisionZero(); case 1: decisionOne(); case 2: decisionTwo(); case 3: decisionThree(); case 4: decisionFour(); } break; case ""w"": System.out.println(""You chose west.""); System.out.println(gettingCloser); decisionSix(); break; } } public static void decisionSix() { System.out.println(""Decision Point 6""); System.out.println(""Choose a direction Mr. Mouse""); String direction = scan.nextLine(); int rndDecion = (int)(Math.random()*5); switch (direction.toLowerCase()) { case ""n"": System.out.println(""You chose north.""); System.out.println(deadEnd); switch (rndDecion) { case 0: decisionZero(); case 1: decisionOne(); case 2: decisionTwo(); case 3: decisionThree(); case 4: decisionFour(); } break; case ""s"": System.out.println(""You chose south.""); System.out.println(deadEnd); switch (rndDecion) { case 0: decisionZero(); case 1: decisionOne(); case 2: decisionTwo(); case 3: decisionThree(); case 4: decisionFour(); } break; case ""e"": System.out.println(""You chose east.""); System.out.println(""Victory cheese!""); break; case ""w"": System.out.println(""You chose west.""); System.out.println(gettingCloser); switch (rndDecion) { case 0: decisionZero(); case 1: decisionOne(); case 2: decisionTwo(); case 3: decisionThree(); case 4: decisionFour(); } break; } } // the main method is COMPLETE. Add/change nothing here. public static void main(String[] args) { decisionZero(); //only line in main method. } }"; RegexOptions options = RegexOptions.Multiline; Regex regex = new Regex(pattern, options); string result = regex.Replace(input, substitution); } }

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for C#, please visit: https://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex(v=vs.110).aspx