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

/
/
g

Test String

Code Generator

Language

Generated Code

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`Connection reset.*?\b([^ .]+\.xls)\b`) var str = `ava.net.SocketException: Connection reset at java.net.SocketInputStream.read(SocketInputStream.java:197) at jcifs.netbios.SessionServicePacket.readPacketType(SessionServicePacket.java:68) at jcifs.netbios.NbtSocket.connect(NbtSocket.java:107) at jcifs.netbios.NbtSocket.(NbtSocket.java:68) at jcifs.smb.SmbTransport.ensureOpen(SmbTransport.java:275) at jcifs.smb.SmbTransport.send(SmbTransport.java:602) at jcifs.smb.SmbTransport.negotiate(SmbTransport.java:847) at jcifs.smb.SmbTree.treeConnect(SmbTree.java:119) at jcifs.smb.SmbFile.connect(SmbFile.java:790) at jcifs.smb.SmbFile.connect0(SmbFile.java:760) at jcifs.smb.SmbFile.queryPath(SmbFile.java:1149) at jcifs.smb.SmbFile.exists(SmbFile.java:1232) at com.ssc.faw.util.SmbFileOperator.copyFile(Unknown Source) at com.ssc.faw.newnav2faw.FundList.checkFiles(Unknown Source) at com.ssc.faw.newnav2faw.FundList.buildList(Unknown Source) at com.ssc.faw.newnav2faw.Process.buildFundList(Unknown Source) at com.ssc.faw.job.NavToFaw.runNav2Faw(Unknown Source) at com.ssc.faw.job.NavToFaw.runNav2Faw(Unknown Source) at com.ssc.faw.job.NavToFaw.runJob(Unknown Source) at com.ssc.faw.job.NavToFaw.main(Unknown Source) [WARN ] 2015-05-05 21:02:26,383 Caught an Exception for file \ac_asd_2.my_web.com\global\nvice\alert\ filename abcd123.xls continuing to process other funds 0 : null jcifs.smb.SmbException: An error occured sending the request.` 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/