Regular Expressions 101

Save & Share

  • Regex Version: ver. 1
  • Update Regex
    ctrl+⇧+s
  • Save new Regex
    ctrl+s
  • Add to Community Library

Flavor

  • PCRE2 (PHP >=7.3)
  • PCRE (PHP <7.3)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java 8
  • .NET 7.0 (C#)
  • Rust
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests

Tools

Sponsors
There are currently no sponsors. Become a sponsor today!
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

r"
"
gm

Test String

Code Generator

Language

Generated Code

# coding=utf8 # the above tag defines encoding for this document and is for Python 2.x compatibility import re regex = r"<.*?>(\d{1,2})<.*?>\s*<.*?>(.*?)<.*?>\s*<.*?>(.*?)<.*?>" test_str = ("<head><title>Popular Baby Names</title>\n" "<meta name=\"dc.language\" scheme=\"ISO639-2\" content=\"eng\">\n" "<meta name=\"dc.creator\" content=\"OACT\">\n" "<meta name=\"lead_content_manager\" content=\"JeffK\">\n" "<meta name=\"coder\" content=\"JeffK\">\n" "<meta name=\"dc.date.reviewed\" scheme=\"ISO8601\" content=\"2006-03-10\">\n" "<link rel=\"stylesheet\" href=\"../OACT/templatefiles/master.css\" type=\"text/css\" media=\"screen\">\n" "<link rel=\"stylesheet\" href=\"../OACT/templatefiles/print.css\" type=\"text/css\" media=\"print\">\n" "</head>\n" "<body bgcolor=\"#ffffff\" text=\"#000000\" topmargin=\"1\" leftmargin=\"0\">\n" "<table width=\"100%\" border=\"0\" cellspacing=\"0\" cellpadding=\"4\">\n" " <tbody>\n" " <tr> \n" " <td class=\"sstop\" valign=\"bottom\" align=\"left\" width=\"25%\">\n" " Social Security Online\n" " </td>\n" " <td valign=\"bottom\" class=\"titletext\">\n" " <!-- sitetitle -->Popular Baby Names\n" " </td>\n" " </tr>\n" " <tr bgcolor=\"#333366\"><td colspan=\"2\" height=\"1\"></td></tr>\n" " <tr>\n" " <td class=\"graystars\" width=\"25%\" valign=\"top\">\n" " <a href=\"../OACT/babynames/\">Popular Baby Names</a></td>\n" " <td valign=\"top\"> \n" " <a href=\"http://www.ssa.gov/\"><img src=\"/templateimages/tinylogo.gif\"\n" " width=\"52\" height=\"47\" align=\"left\"\n" " alt=\"SSA logo: link to Social Security home page\" border=\"0\"></a>\n" " <h1>Popular Names by Birth Year</h1>September 11, 2014</td>\n" " </tr>\n" "</tbody></table>\n" "<script type=\"text/javascript\" src=\"../OACT/babynames/chkinput.js\"></script>\n\n" "<table width=\"100%\" border=\"0\" cellspacing=\"0\" cellpadding=\"4\" summary=\"formatting\">\n" " <tr valign=\"top\">\n" " <td width=\"25%\" class=\"greycell\">\n" " <a href=\"../OACT/babynames/background.html\">Background information</a>\n" " <p><br />\n" " &nbsp; Select another <label for=\"yob\">year of birth</label>?<br />\n" " <form name=\"popnames\" method=\"post\" action=\"/cgi-bin/popularnames.cgi\"\n" " onSubmit=\"return submitIt();\">\n" " &nbsp; <input type=\"text\" name=\"year\" id=\"yob\" size=\"4\" value=\"2012\"><input type=\"hidden\" name=\"top\" value=\"25\"><input type=\"hidden\" name=\"number\" value=\"\">\n" " &nbsp; <input type=\"submit\" value=\" Go \"></form>\n" " </td>\n" " <td><p align=\"center\"><table width=\"$tablewidth\" border=\"1\" bordercolor=\"#aaabbb\" cellpadding=\"2\" cellspacing=\"0\" summary=\"Popularity for top 25\">\n" " <caption><h2>Popularity in 2012</h2></caption>\n" " <tr align=\"center\" valign=\"bottom\">\n" " <th scope=\"col\" width=\"12%\" bgcolor=\"#efefef\">Rank</th>\n" " <th scope=\"col\" width=\"$colwidth\" bgcolor=\"#99ccff\">Male name</th>\n" " <th scope=\"col\" bgcolor=\"pink\" width=\"41%\">Female name</th></tr>\n" "<tr align=\"right\">\n" " <td>1</td> <td>Jacob</td> <td>Sophia</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>2</td> <td>Mason</td> <td>Emma</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>3</td> <td>Ethan</td> <td>Isabella</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>4</td> <td>Noah</td> <td>Olivia</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>5</td> <td>William</td> <td>Ava</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>6</td> <td>Liam</td> <td>Emily</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>7</td> <td>Michael</td> <td>Abigail</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>8</td> <td>Jayden</td> <td>Mia</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>9</td> <td>Alexander</td> <td>Madison</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>10</td> <td>Aiden</td> <td>Elizabeth</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>11</td> <td>Daniel</td> <td>Chloe</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>12</td> <td>Matthew</td> <td>Ella</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>13</td> <td>Elijah</td> <td>Avery</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>14</td> <td>James</td> <td>Addison</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>15</td> <td>Anthony</td> <td>Aubrey</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>16</td> <td>Benjamin</td> <td>Lily</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>17</td> <td>Joshua</td> <td>Natalie</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>18</td> <td>Andrew</td> <td>Sofia</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>19</td> <td>Joseph</td> <td>Charlotte</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>20</td> <td>David</td> <td>Zoey</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>21</td> <td>Jackson</td> <td>Grace</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>22</td> <td>Logan</td> <td>Hannah</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>23</td> <td>Christopher</td> <td>Amelia</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>24</td> <td>Gabriel</td> <td>Harper</td>\n" "</tr>\n" "<tr align=\"right\">\n" " <td>25</td> <td>Samuel</td> <td>Lillian</td>\n" "</tr>\n" "<tr><td colspan=\"3\"><small>Note: Rank 1 is the most popular,\n" "rank 2 is the next most popular, and so forth. \n" "</table></p>\n" "</td></tr></table>\n" "<table class=\"printhide\" width=\"100%\" border=\"0\" cellpadding=\"1\" cellspacing=\"0\">\n" " <tr bgcolor=\"#333366\"><td height=\"1\" colspan=\"2\"></td></tr>\n" " <tr>\n" " <td width=\"26%\" valign=\"middle\">&nbsp;</td>\n" " <td valign=\"top\" class=\"seventypercent\">\n" " <a href=\"http://www.ssa.gov/privacy.html\">Privacy Policy</a>&nbsp;\n" " | <a href=\"http://www.ssa.gov/websitepolicies.htm\">Website Policies\n" " &amp; Other Important Information</a>&nbsp;\n" " | <a href=\"http://www.ssa.gov/sitemap.htm\">Site Map</a></td>\n" " </tr>\n" "</table>\n" "</body></html>") matches = re.finditer(regex, test_str, re.MULTILINE) for matchNum, match in enumerate(matches, start=1): print ("Match {matchNum} was found at {start}-{end}: {match}".format(matchNum = matchNum, start = match.start(), end = match.end(), match = match.group())) for groupNum in range(0, len(match.groups())): groupNum = groupNum + 1 print ("Group {groupNum} found at {start}-{end}: {group}".format(groupNum = groupNum, start = match.start(groupNum), end = match.end(groupNum), group = match.group(groupNum))) # Note: for Python 2.7 compatibility, use ur"" to prefix the regex and u"" to prefix the test string and 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 Python, please visit: https://docs.python.org/3/library/re.html