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

/
/
gm

Test String

Code Generator

Language

Generated Code

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`(?m)^(mongodb(?:\+srv)?(\:)(?:\/{2}){1})(?:\w+\:\w+\@)?(\w+?(?:\.\w+?)*)(\:)(\d+(?:\/){0,1})(?:\/\w+?)?(?:\?\w+?\=\w+?(?:\&\w+?\=\w+?)*)?$`) var str = `// Do not work // mongodb://username:localhost:27107/adfaeadf mongodb://username:@localhost:27107/adfaeadf mongodb://:password@localhost:27107/adfaeadf mongodb://:@localhost:27107/mydatabasename mongodb://@localhost:27107/mydatabasename mongodb:/ddd:333/fffvv mongodb:username:password@localhost:27107/mydatabasename mongodb://localhost:27107fffsfsf mongodb://localhost:27107/mydatabasename/?option=val // should validate // mongodb://localhost:27107/mydatabasename mongodb://user:pass@localhost:27107/mydatabasename mongodb://user:pass@localhost:27107/MYDATABASENAME mongodb+srv://localhost:333/ff mongodb://localhost:27107/mydatabasename?option=val mongodb://localhost:27107/mydatabasename?option=val&secondOption=val mongodb://localhost:27107 mongodb://localhost:27107/ mongodb://dbexample.com:2333 mongodb://another.example.com:2555 ` 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/