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
No Match

@"
"
gmi

Test String

Code Generator

Language

Generated Code

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`(?mi)^\s*Failed\s(.*)([\s\S]*?)(Stack\sTrace:\s*at\s)(.*)\s+in\s+(.*):line\s+(\d+)\s*$`) var str = `Test run for /home/runner/work/Library/Library.Tests/bin/Debug/net7.0/Library.Tests.dll (.NETCoreApp,Version=v7.0) Microsoft (R) Test Execution Command Line Tool Version 17.7.0-preview-23364-03+bc17bb9693cfc4778ded51aa0ab7f1065433f989 (x64) Copyright (c) Microsoft Corporation. All rights reserved. Starting test execution, please wait... A total of 1 test files matched the specified pattern. [xUnit.net 00:00:00.55] Library.Tests.UnitTest1.DeliberateFail2 [FAIL] [xUnit.net 00:00:00.56] Library.Tests.UnitTest1.DeliberateFail1 [FAIL] Failed Library.Tests.UnitTest1.DeliberateFail2 [< 1 ms] Error Message: System.Exception : Error message Stack Trace: at Library.Tests.UnitTest1.DeliberateFail2() in /home/runner/work/Library/Library.Tests/UnitTest1.cs:line 30 at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor) at System.Reflection.MethodInvoker.Invoke(Object obj, IntPtr* args, BindingFlags invokeAttr) Failed Library.Tests.UnitTest1.DeliberateFail1 [< 1 ms] Error Message: Assert.True() Failure Expected: True Actual: False Stack Trace: at Library.Tests.UnitTest1.DeliberateFail1() in /home/runner/work/Library/Library.Tests/UnitTest1.cs:line 27 at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor) at System.Reflection.MethodInvoker.Invoke(Object obj, IntPtr* args, BindingFlags invokeAttr) Results File: /home/runner/work/Library/Library.Tests/TestResults/test-results.trx Failed! - Failed: 2, Passed: 133, Skipped: 0, Total: 135, Duration: 549 ms - Library.Tests.dll (net7.0) Error: Process completed with exit code 1.` for i, match := range re.FindAllString(str, -1) { fmt.Println(match, "found at index", i) } }

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 Golang, please visit: https://golang.org/pkg/regexp/