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

/
/
g

Test String

Code Generator

Generated Code

use strict; my $str = '<!DOCTYPE html> <html> <head> <title>Newest Questions - Page 2 - Electrical Engineering Stack Exchange</title> <link rel="shortcut icon" href="//cdn.sstatic.net/electronics/img/favicon.ico"> <link rel="apple-touch-icon image_src" href="//cdn.sstatic.net/electronics/img/apple-touch-icon.png"> <link rel="search" type="application/opensearchdescription+xml" title="Electrical Engineering Stack Exchange" href="/opensearch.xml"> <script type="text/javascript" src="//ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script> <script type="text/javascript" src="//cdn.sstatic.net/js/stub.js?v=5d233283ca8d"></script> <link rel="stylesheet" type="text/css" href="//cdn.sstatic.net/electronics/all.css?v=672ddec9ce04"> <script type="text/x-mathjax-config"> MathJax.Hub.Config({"HTML-CSS": { preferredFont: "TeX", availableFonts: ["STIX","TeX"], linebreaks: { automatic:true }, EqnChunk: (MathJax.Hub.Browser.isMobile ? 10 : 50) }, tex2jax: { inlineMath: [ ["\\\\$", "\\\\$"] ], displayMath: [ ["$$","$$"], ["\\\\[", "\\\\]"] ], processEscapes: true, ignoreClass: "tex2jax_ignore|dno" }, TeX: { noUndefined: { attributes: { mathcolor: "red", mathbackground: "#FFEEEE", mathsize: "90%" } }, Macros: { href: "{}" } }, messageStyle: "none" }); </script> <script type="text/javascript" src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS_HTML"></script> <script type="text/javascript"> StackExchange.ready(function () { StackExchange.realtime.init(\'sockets.ny.stackexchange.com\'); StackExchange.realtime.subscribeToInboxNotifications(); StackExchange.realtime.subscribeToReputationNotifications(\'135\'); }); </script> <script type="text/javascript"> StackExchange.init({"stackAuthUrl":"https://stackauth.com","serverTime":1377686462,"styleCode":true,"enableUserHovercards":true,"site":{"name":"Electrical Engineering Stack Exchange","description":"Q&A for electronics and electrical engineering professionals, students, and enthusiasts","isNoticesTabEnabled":true,"recaptchaPublicKey":"6LdsB7sSAAAAAAzjgEF_Hd8vXv-C42sa_KyofaGR","enableSocialMediaInSharePopup":true},"user":{"fkey":"964caaf8350dc8ae69af722ba29b4a1d","isAnonymous":true}}); StackExchange.using.setCacheBreakers({"js/prettify-full.js":"6c261bebf56a","js/moderator.js":"ed7a8238b2f8","js/full-anon.js":"5f9bf5810297","js/full.js":"027ac5ea264e","js/wmd.js":"cff10cca4fd9","js/third-party/jquery.autocomplete.min.js":"e5f01e97f7c3","js/mobile.js":"82a79dbb7259","js/help.js":"6e6623243cf6","js/tageditor.js":"450c9e8426fc","js/tageditornew.js":"b6c68ad4c7dd","js/inline-tag-editing.js":"8e84e8a137f7","js/revisions.js":"d3e781ee5528","js/review.js":"947758ba83ea","js/tagsuggestions.js":"aa48ef6154df","js/post-validation.js":"bb996020492a","js/explore-qlist.js":"1c5bbd79b562","js/events.js":"27a33f0b2cad"}); StackExchange.using.setCacheBreakers({"js/mathjax-editing.js":"6da1b6cfe19f","js/external-editor.js":"51c0a8d46d29"}); </script> <script type="text/javascript"> StackExchange.using("gps", function() { StackExchange.gps.init(true); }); </script> <script type="text/javascript"> StackExchange.ready(function () { $(\'#nav-tour\').click(function () { StackExchange.using("gps", function() { StackExchange.gps.track("aboutpage.click", { aboutclick_location: "headermain" }, true); }); }); }); </script> </head> <body class="questions-page"> <noscript><div id="noscript-padding"></div></noscript> <div id="notify-container"></div> <div id="overlay-header"></div> <div id="custom-header"></div> <div class="container"> <div id="header" class=headeranon> <div id="portalLink"> <a class="genu" href="http://stackexchange.com" onclick="StackExchange.ready(function(){genuwine.click();});return false;">Stack Exchange</a> </div> <div id="topbar"> <div id="hlinks"> <span id="hlinks-user"></span> <span id="hlinks-nav"> <a href="/users/login?returnurl=%2fquestions%3fpage%3d2%26sort%3dnewest">sign up</a> <span class="lsep">|</span> <a href="/users/login?returnurl=%2fquestions%3fpage%3d2%26sort%3dnewest">log in</a> <span class="lsep">|</span> </span> <span id="hlinks-custom"></span> </div> <div id="hsearch"> <form id="search" action="/search" method="get" autocomplete="off"> <div> <input autocomplete="off" name="q" class="textbox" placeholder="search" tabindex="1" type="text" maxlength="240" size="28" value=""> </div> </form> </div> </div> <br class="cbt"> <div id="hlogo"> <a href="/"> Electrical Engineering </a> </div> <div id="hmenus"> <div class="nav mainnavs mainnavsanon"> <ul> <li class="youarehere"><a id="nav-questions" href="/questions">Questions</a></li> <li><a id="nav-tags" href="/tags">Tags</a></li> <li><a id="nav-tour" href="/about">Tour</a></li> <li><a id="nav-users" href="/users">Users</a></li> </ul> </div> <div class="nav askquestion"> <ul> <li> <a id="nav-askquestion" href="/questions/ask">Ask Question</a> </li> </ul> </div> </div> </div> <div id="content"> <div id="mainbar"> <div class="subheader"> <h1 id="h-all-questions">All Questions</h1> <div id="tabs"> <a class="youarehere" href="/questions?sort=newest" title="the most recently asked questions">newest</a> <a href="/questions?sort=featured" title="questions with open bounties"><span class=\'bounty-indicator-tab\'>3</span>featured</a> <a href="/questions?sort=frequent" title="questions with the most links">frequent</a> <a href="/questions?sort=votes" title="questions with the most votes">votes</a> <a href="/questions?sort=active" title="questions that have recent activity">active</a> <a href="/questions?sort=unanswered" title="questions that have no upvoted answers">unanswered</a> </div> </div> <div id="questions"> <div class="question-summary" id="question-summary-80417"> <div class="statscontainer"> <div class="statsarrow"></div> <div class="stats"> <div class="vote"> <div class="votes"> <span class="vote-count-post "><strong>1</strong></span> <div class="viewcount">vote</div> </div> </div> <div class="status answered"> <strong>2</strong>answers </div> </div> <div class="views " title="65 views"> 65 views </div> </div> <div class="summary"> <h3><a href="/questions/80417/can-i-safely-enclose-battery-powered-electronics-in-an-antistatic-bag-to-protect" class="question-hyperlink">Can I safely enclose battery-powered electronics in an antistatic bag to protect it from static electricity?</a></h3> <div class="excerpt"> I am building an enclosure for a Beaglebone and external circuit that I want to be able to wear, and therefore want to be lightweight and somewhat comfortable. I power the Beaglebone using a battery ... </div> <div class="tags t-shielding t-antistatic t-static"> <a href="/questions/tagged/shielding" class="post-tag" title="show questions tagged \'shielding\'" rel="tag">shielding</a> <a href="/questions/tagged/antistatic" class="post-tag" title="show questions tagged \'antistatic\'" rel="tag">antistatic</a> <a href="/questions/tagged/static" class="post-tag" title="show questions tagged \'static\'" rel="tag">static</a> </div> <div class="started fr"> <div class="user-info "> <div class="user-action-time"> asked <span title="2013-08-27 22:47:03Z" class="relativetime">11 hours ago</span> </div> <div class="user-gravatar32"> <a href="/users/19783/mokogobo"><div class=""><img src="https://www.gravatar.com/avatar/045025756373a85e8336c8126ee006c6?s=32&d=identicon&r=PG" alt="" width="32" height="32"></div></a> </div> <div class="user-details"> <a href="/users/19783/mokogobo">mokogobo</a><br> <span class="reputation-score" title="reputation score" dir="ltr">31</span><span title="4 bronze badges"><span class="badge3"></span><span class="badgecount">4</span></span> </div> </div> </div> </div> </div> <div class="question-summary" id="question-summary-80412"> <div class="statscontainer"> <div class="statsarrow"></div> <div class="stats"> <div class="vote"> <div class="votes"> <span class="vote-count-post "><strong>0</strong></span> <div class="viewcount">votes</div> </div> </div> <div class="status answered"> <strong>1</strong>answer </div> </div> <div class="views " title="22 views"> 22 views </div> </div> <div class="summary"> <h3><a href="/questions/80412/how-to-overwrite-flash-memory-on-stm32l-series" class="question-hyperlink">How to overwrite flash memory on STM32L series</a></h3> <div class="excerpt"> I am trying to write a known pattern (ie 0xFFFFFFFF or 0x00000000) on top of already written flash memory, to invalidate portions of it for a primitive file system. But it doesn\'t work for me on the ... </div> <div class="tags t-stm32 t-flash"> <a href="/questions/tagged/stm32" class="post-tag" title="show questions tagged \'stm32\'" rel="tag">stm32</a> <a href="/questions/tagged/flash" class="post-tag" title="show questions tagged \'flash\'" rel="tag">flash</a> </div> <div class="started fr"> <div class="user-info "> <div class="user-action-time"> asked <span title="2013-08-27 22:09:01Z" class="relativetime">12 hours ago</span> </div> <div class="user-gravatar32"> <a href="/users/15757/mark-lakata"><div class=""><img src="https://www.gravatar.com/avatar/5fd80d98f96f9adbde7876cbda181715?s=32&d=identicon&r=PG" alt="" width="32" height="32"></div></a> </div> <div class="user-details"> <a href="/users/15757/mark-lakata">Mark Lakata</a><br> <span class="reputation-score" title="reputation score" dir="ltr">111</span><span title="2 bronze badges"><span class="badge3"></span><span class="badgecount">2</span></span> </div> </div> </div> </div> </div> <div class="question-summary" id="question-summary-80407"> <div class="statscontainer"> <div class="statsarrow"></div> <div class="stats"> <div class="vote"> <div class="votes"> <span class="vote-count-post "><strong>2</strong></span> <div class="viewcount">votes</div> </div> </div> <div class="status answered"> <strong>1</strong>answer </div> </div> <div class="views " title="61 views"> 61 views </div> </div> <div class="summary"> <h3><a href="/questions/80407/about-power-supply-of-opertional-amplifier" class="question-hyperlink">about power supply of opertional amplifier</a></h3> <div class="excerpt"> I am constructing an operational amplifier as shown in the following figure. I use a batter as supplier for the OP Amp and set it up as a non-inverting amp circuit. I saw that the output was clipped ... </div> <div class="tags t-op-amp"> <a href="/questions/tagged/op-amp" class="post-tag" title="show questions tagged \'op-amp\'" rel="tag">op-amp</a> </div> <div class="started fr"> <div class="user-info "> <div class="user-action-time"> asked <span title="2013-08-27 21:49:14Z" class="relativetime">12 hours ago</span> </div> <div class="user-gravatar32"> <a href="/users/17060/user1285419"><div class=""><img src="https://www.gravatar.com/avatar/08ee68b20a4eceff26f7eee99b708c08?s=32&d=identicon&r=PG" alt="" width="32" height="32"></div></a> </div> <div class="user-details"> <a href="/users/17060/user1285419">user1285419</a><br> <span class="reputation-score" title="reputation score" dir="ltr">165</span><span title="5 bronze badges"><span class="badge3"></span><span class="badgecount">5</span></span> </div> </div> </div> </div> </div> <div class="question-summary" id="question-summary-80405"> <div class="statscontainer"> <div class="statsarrow"></div> <div class="stats"> <div class="vote"> <div class="votes"> <span class="vote-count-post "><strong>4</strong></span> <div class="viewcount">votes</div> </div> </div> <div class="status answered-accepted"> <strong>2</strong>answers </div> </div> <div class="views " title="64 views"> 64 views </div> </div> <div class="summary"> <h3><a href="/questions/80405/5v-regulator-power-dissipation" class="question-hyperlink">5V Regulator Power Dissipation</a></h3> <div class="excerpt"> I am using a 5V regulator (LP2950) from ON Semiconductor. I am using this for USB power and I\'m feeding in 9V from an adapter. USB requires maximum of 500mA right? So the maximum power dissipation in ... </div> <div class="tags t-voltage-regulator t-surface-mount t-heatsink t-5v t-power-dissipation"> <a href="/questions/tagged/voltage-regulator" class="post-tag" title="show questions tagged \'voltage-regulator\'" rel="tag">voltage-regulator</a> <a href="/questions/tagged/surface-mount" class="post-tag" title="show questions tagged \'surface-mount\'" rel="tag">surface-mount</a> <a href="/questions/tagged/heatsink" class="post-tag" title="show questions tagged \'heatsink\'" rel="tag">heatsink</a> <a href="/questions/tagged/5v" class="post-tag" title="show questions tagged \'5v\'" rel="tag">5v</a> <a href="/questions/tagged/power-dissipation" class="post-tag" title="show questions tagged \'power-dissipation\'" rel="tag">power-dissipation</a> </div> <div class="started fr"> <div class="user-info "> <div class="user-action-time"> asked <span title="2013-08-27 21:39:31Z" class="relativetime">13 hours ago</span> </div> <div class="user-gravatar32"> <a href="/users/10082/david-norman"><div class=""><img src="https://www.gravatar.com/avatar/8b073417e471077280b3fc5ff2eaf1f7?s=32&d=identicon&r=PG" alt="" width="32" height="32"></div></a> </div> <div class="user-details"> <a href="/users/10082/david-norman">David Norman</a><br> <span class="reputation-score" title="reputation score" dir="ltr">322</span><span title="3 silver badges"><span class="badge2"></span><span class="badgecount">3</span></span><span title="10 bronze badges"><span class="badge3"></span><span class="badgecount">10</span></span> </div> </div> </div> </div> </div> <div class="question-summary" id="question-summary-80404"> <div class="statscontainer"> <div class="statsarrow"></div> <div class="stats"> <div class="vote"> <div class="votes"> <span class="vote-count-post "><strong>0</strong></span> <div class="viewcount">votes</div> </div> </div> <div class="status answered"> <strong>1</strong>answer </div> </div> <div class="views " title="44 views"> 44 views </div> </div> <div class="summary"> <h3><a href="/questions/80404/how-to-stop-two-dc-motors-simultaneously-using-limit-switches" class="question-hyperlink">How to stop two DC motors simultaneously using limit switches</a></h3> <div class="excerpt"> I need some help - I\'m building a machine but I\'m not sure of the best way of doing it. I have three large wire spools. Two empty and one full. The full spool (approx. 500kg) is much larger than the ... </div> <div class="tags t-dc-motor t-switch-mode-power-supply t-servo t-plc t-toggle-switch"> <a href="/questions/tagged/dc-motor" class="post-tag" title="show questions tagged \'dc-motor\'" rel="tag">dc-motor</a> <a href="/questions/tagged/switch-mode-power-supply" class="post-tag" title="show questions tagged \'switch-mode-power-supply\'" rel="tag">switch-mode-power-supply</a> <a href="/questions/tagged/servo" class="post-tag" title="show questions tagged \'servo\'" rel="tag">servo</a> <a href="/questions/tagged/plc" class="post-tag" title="show questions tagged \'plc\'" rel="tag">plc</a> <a href="/questions/tagged/toggle-switch" class="post-tag" title="show questions tagged \'toggle-switch\'" rel="tag">toggle-switch</a> </div> <div class="started fr"> <div class="user-info "> <div class="user-action-time"> asked <span title="2013-08-27 21:29:47Z" class="relativetime">13 hours ago</span> </div> <div class="user-gravatar32"> <a href="/users/28090/golden-bucky"><div class=""><img src="https://www.gravatar.com/avatar/0d00cc71566104e18dc131bc7f5b4cf1?s=32&d=identicon&r=PG&f=1" alt="" width="32" height="32"></div></a> </div> <div class="user-details"> <a href="/users/28090/golden-bucky">Golden Bucky</a><br> <span class="reputation-score" title="reputation score" dir="ltr">1</span> </div> </div> </div> </div> </div> <div class="question-summary" id="question-summary-80396"> <div class="statscontainer"> <div class="statsarrow"></div> <div class="stats"> <div class="vote"> <div class="votes"> <span class="vote-count-post "><strong>1</strong></span> <div class="viewcount">vote</div> </div> </div> <div class="status answered"> <strong>1</strong>answer </div> </div> <div class="views " title="58 views"> 58 views </div> </div> <div class="summary"> <h3><a href="/questions/80396/logic-level-translator-caveats" class="question-hyperlink">Logic Level Translator caveats</a></h3> <div class="excerpt"> I have a device that runs on 2.5Vcmos logic levels, there are about a half dozen ic\'s with a mixture of parallel and serial (TWI and I2C) signal lines. Rather than placing my own uC on the board I\'d ... </div> <div class="tags t-level-translation"> <a href="/questions/tagged/level-translation" class="post-tag" title="show questions tagged \'level-translation\'" rel="tag">level-translation</a> </div> <div class="started fr"> <div class="user-info "> <div class="user-action-time"> asked <span title="2013-08-27 20:45:03Z" class="relativetime">13 hours ago</span> </div> <div class="user-gravatar32"> <a href="/users/1729/crasic"><div class=""><img src="https://www.gravatar.com/avatar/61084e40f265986dd41136b4f3dc028f?s=32&d=identicon&r=PG" alt="" width="32" height="32"></div></a> </div> <div class="user-details"> <a href="/users/1729/crasic">crasic</a><br> <span class="reputation-score" title="reputation score" dir="ltr">643</span><span title="2 silver badges"><span class="badge2"></span><span class="badgecount">2</span></span><span title="8 bronze badges"><span class="badge3"></span><span class="badgecount">8</span></span> </div> </div> </div> </div> </div> <div class="question-summary" id="question-summary-80393"> <div class="statscontainer"> <div class="statsarrow"></div> <div class="stats"> <div class="vote"> <div class="votes"> <span class="vote-count-post "><strong>1</strong></span> <div class="viewcount">vote</div> </div> </div> <div class="status answered"> <strong>1</strong>answer </div> </div> <div class="views " title="57 views"> 57 views </div> </div> <div class="summary"> <h3><a href="/questions/80393/microcontroller-newbe-here-led-color-pattern-controller-for-arcade-machine" class="question-hyperlink">Microcontroller Newbe here. LED color pattern controller for arcade machine [on hold]</a></h3> <div class="excerpt"> I am building an arcade machine and I want to make a cool led light display for the marquee. You can see pictures of what I\'m talking about here. I want to light up each one of those holes with ... </div> <div class="tags t-microcontroller t-led"> <a href="/questions/tagged/microcontroller" class="post-tag" title="show questions tagged \'microcontroller\'" rel="tag">microcontroller</a> <a href="/questions/tagged/led" class="post-tag" title="show questions tagged \'led\'" rel="tag">led</a> </div> <div class="started fr"> <div class="user-info "> <div class="user-action-time"> asked <span title="2013-08-27 20:34:56Z" class="relativetime">14 hours ago</span> </div> <div class="user-gravatar32"> <a href="/users/28086/doug-steinberg"><div class=""><img src="https://www.gravatar.com/avatar/f8a5cf563e719e934263883978ab80f1?s=32&d=identicon&r=PG" alt="" width="32" height="32"></div></a> </div> <div class="user-details"> <a href="/users/28086/doug-steinberg">Doug Steinberg</a><br> <span class="reputation-score" title="reputation score" dir="ltr">6</span><span title="1 bronze badge"><span class="badge3"></span><span class="badgecount">1</span></span> </div> </div> </div> </div> </div> <div class="question-summary" id="question-summary-80385"> <div class="statscontainer"> <div class="statsarrow"></div> <div class="stats"> <div class="vote"> <div class="votes"> <span class="vote-count-post "><strong>1</strong></span> <div class="viewcount">vote</div> </div> </div> <div class="status answered"> <strong>2</strong>answers </div> </div> <div class="views " title="69 views"> 69 views </div> </div> <div class="summary"> <h3><a href="/questions/80385/how-to-scale-dynamic-range-voltage-to-1-5-volt" class="question-hyperlink">how to scale dynamic range voltage to 1-5 volt</a></h3> <div class="excerpt"> how can i make circuit that scale input voltage that have dynamic range to 1-5 volt output? the circuit will have Vref+ and Vref- as maximum and minimum for Vinput and then scale to 1-5 volt output ... </div> <div class="tags t-voltage t-amplifier"> <a href="/questions/tagged/voltage" class="post-tag" title="show questions tagged \'voltage\'" rel="tag">voltage</a> <a href="/questions/tagged/amplifier" class="post-tag" title="show questions tagged \'amplifier\'" rel="tag">amplifier</a> </div> <div class="started fr"> <div class="user-info "> <div class="user-action-time"> asked <span title="2013-08-27 19:30:33Z" class="relativetime">15 hours ago</span> </div> <div class="user-gravatar32"> <a href="/users/28084/user28084"><div class=""><img src="https://www.gravatar.com/avatar/2cacd24f99b2bcbd8236d1ce8c3c559f?s=32&d=identicon&r=PG&f=1" alt="" width="32" height="32"></div></a> </div> <div class="user-details"> <a href="/users/28084/user28084">user28084</a><br> <span class="reputation-score" title="reputation score" dir="ltr">9</span><span title="2 bronze badges"><span class="badge3"></span><span class="badgecount">2</span></span> </div> </div> </div> </div> </div> <div class="question-summary" id="question-summary-80383"> <div class="statscontainer"> <div class="statsarrow"></div> <div class="stats"> <div class="vote"> <div class="votes"> <span class="vote-count-post "><strong>0</strong></span> <div class="viewcount">votes</div> </div> </div> <div class="status answered-accepted"> <strong>1</strong>answer </div> </div> <div class="views " title="38 views"> 38 views </div> </div> <div class="summary"> <h3><a href="/questions/80383/is-it-the-frequency-that-determines-the-current-in-a-lc-tank-parallel-circuit" class="question-hyperlink">Is it the frequency that determines the current in a LC Tank Parallel Circuit?</a></h3> <div class="excerpt"> Jump a head to the question if you aren\'t interested in the background of my project Background of my project I want to create objects of metal. So I need to be able to cast a metal. Aluminium seems ... </div> <div class="tags t-current t-frequency t-solenoid t-induction t-rlc"> <a href="/questions/tagged/current" class="post-tag" title="show questions tagged \'current\'" rel="tag">current</a> <a href="/questions/tagged/frequency" class="post-tag" title="show questions tagged \'frequency\'" rel="tag">frequency</a> <a href="/questions/tagged/solenoid" class="post-tag" title="show questions tagged \'solenoid\'" rel="tag">solenoid</a> <a href="/questions/tagged/induction" class="post-tag" title="show questions tagged \'induction\'" rel="tag">induction</a> <a href="/questions/tagged/rlc" class="post-tag" title="show questions tagged \'rlc\'" rel="tag">rlc</a> </div> <div class="started fr"> <div class="user-info "> <div class="user-action-time"> asked <span title="2013-08-27 19:29:24Z" class="relativetime">15 hours ago</span> </div> <div class="user-gravatar32"> <a href="/users/26135/mike-de-klerk"><div class=""><img src="https://www.gravatar.com/avatar/7c2d61f7fedb644912d1cef5ed0b250a?s=32&d=identicon&r=PG" alt="" width="32" height="32"></div></a> </div> <div class="user-details"> <a href="/users/26135/mike-de-klerk">Mike de Klerk</a><br> <span class="reputation-score" title="reputation score" dir="ltr">183</span><span title="6 bronze badges"><span class="badge3"></span><span class="badgecount">6</span></span> </div> </div> </div> </div> </div> <div class="question-summary" id="question-summary-80378"> <div class="statscontainer"> <div class="statsarrow"></div> <div class="stats"> <div class="vote"> <div class="votes"> <span class="vote-count-post "><strong>4</strong></span> <div class="viewcount">votes</div> </div> </div> <div class="status answered-accepted"> <strong>4</strong>answers </div> </div> <div class="views " title="54 views"> 54 views </div> </div> <div class="summary"> <h3><a href="/questions/80378/replacing-resistors-with-equivalent-resistor" class="question-hyperlink">Replacing resistors with equivalent resistor</a></h3> <div class="excerpt"> This is somewhat a homework assignment, but please bear with me. Given the following schematic, I want to know the overall resistance when measured from node A to node B. simulate this circuit ... </div> <div class="tags t-resistors t-resistance t-circuit-analysis"> <a href="/questions/tagged/resistors" class="post-tag" title="show questions tagged \'resistors\'" rel="tag">resistors</a> <a href="/questions/tagged/resistance" class="post-tag" title="show questions tagged \'resistance\'" rel="tag">resistance</a> <a href="/questions/tagged/circuit-analysis" class="post-tag" title="show questions tagged \'circuit-analysis\'" rel="tag">circuit-analysis</a> </div> <div class="started fr"> <div class="user-info "> <div class="user-action-time"> asked <span title="2013-08-27 19:07:14Z" class="relativetime">15 hours ago</span> </div> <div class="user-gravatar32"> <a href="/users/9913/nijansen"><div class=""><img src="https://www.gravatar.com/avatar/8250825c174a99613ffeec2ccc085bcf?s=32&d=identicon&r=PG" alt="" width="32" height="32"></div></a> </div> <div class="user-details"> <a href="/users/9913/nijansen">nijansen</a><br> <span class="reputation-score" title="reputation score" dir="ltr">174</span><span title="8 bronze badges"><span class="badge3"></span><span class="badgecount">8</span></span> </div> </div> </div> </div> </div> <div class="question-summary" id="question-summary-80371"> <div class="statscontainer"> <div class="statsarrow"></div> <div class="stats"> <div class="vote"> <div class="votes"> <span class="vote-count-post "><strong>2</strong></span> <div class="viewcount">votes</div> </div> </div> <div class="status answered"> <strong>2</strong>answers </div> </div> <div class="views " title="32 views"> 32 views </div> </div> <div class="summary"> <h3><a href="/questions/80371/saturation-current-in-inductor-definition" class="question-hyperlink">Saturation current in inductor - Definition?</a></h3> <div class="excerpt"> Can somebody explain me what actually is a saturation current of an inductor. You may consider one inductor too and explain the things. This is very much confusing for me. Somebody give me a clear cut ... </div> <div class="tags t-inductor"> <a href="/questions/tagged/inductor" class="post-tag" title="show questions tagged \'inductor\'" rel="tag">inductor</a> </div> <div class="started fr"> <div class="user-info "> <div class="user-action-time"> asked <span title="2013-08-27 18:38:03Z" class="relativetime">16 hours ago</span> </div> <div class="user-gravatar32"> <a href="/users/20352/durgaprasad"><div class="gravatar-wrapper-32"><img src="http://i.stack.imgur.com/iQDud.jpg?s=32&g=1" alt=""></div></a> </div> <div class="user-details"> <a href="/users/20352/durgaprasad">Durgaprasad</a><br> <span class="reputation-score" title="reputation score" dir="ltr">339</span><span title="9 bronze badges"><span class="badge3"></span><span class="badgecount">9</span></span> </div> </div> </div> </div> </div> <div class="question-summary" id="question-summary-80370"> <div class="statscontainer"> <div class="statsarrow"></div> <div class="stats"> <div class="vote"> <div class="votes"> <span class="vote-count-post "><strong>3</strong></span> <div class="viewcount">votes</div> </div> </div> <div class="status answered"> <strong>2</strong>answers </div> </div> <div class="views " title="85 views"> 85 views </div> </div> <div class="summary"> <h3><a href="/questions/80370/is-it-possible-for-batteries-to-give-a-false-reading-of-being-charged-with-a-mul" class="question-hyperlink">Is it possible for batteries to give a false reading of being charged with a multimeter?</a></h3> <div class="excerpt"> I bought a Stanley SL5W09L spotlight about four years ago and it has performed wonderfully ever since. Recently however it has stopped working. I can plug it in, and the charge light will come on ... </div> <div class="tags t-batteries"> <a href="/questions/tagged/batteries" class="post-tag" title="show questions tagged \'batteries\'" rel="tag">batteries</a> </div> <div class="started fr"> <div class="user-info "> <div class="user-action-time"> asked <span title="2013-08-27 18:36:29Z" class="relativetime">16 hours ago</span> </div> <div class="user-gravatar32"> <a href="/users/24413/steve-french"><div class=""><img src="https://www.gravatar.com/avatar/ef46e9c26326bd9d82479c7daf4155a3?s=32&d=identicon&r=PG" alt="" width="32" height="32"></div></a> </div> <div class="user-details"> <a href="/users/24413/steve-french">Steve French</a><br> <span class="reputation-score" title="reputation score" dir="ltr">119</span><span title="1 bronze badge"><span class="badge3"></span><span class="badgecount">1</span></span> </div> </div> </div> </div> </div> <div class="question-summary" id="question-summary-80366"> <div class="statscontainer"> <div class="statsarrow"></div> <div class="stats"> <div class="vote"> <div class="votes"> <span class="vote-count-post "><strong>0</strong></span> <div class="viewcount">votes</div> </div> </div> <div class="status answered"> <strong>1</strong>answer </div> </div> <div class="views " title="37 views"> 37 views </div> </div> <div class="summary"> <h3><a href="/questions/80366/arduino-accessing-extra-analog-pins-on-32-pin-smt-package" class="question-hyperlink">Arduino - accessing extra analog pins on 32-pin SMT package</a></h3> <div class="excerpt"> I\'ve got a 32-pin ATMega328 on a breadboard. I have its analog pin #6 as an input pin from another IC on my board. The IC sends data to this analog pin. Now, the ATMega328 DIP package (used on the ... </div> <div class="tags t-arduino"> <a href="/questions/tagged/arduino" class="post-tag" title="show questions tagged \'arduino\'" rel="tag">arduino</a> </div> <div class="started fr"> <div class="user-info "> <div class="user-action-time"> asked <span title="2013-08-27 18:07:58Z" class="relativetime">16 hours ago</span> </div> <div class="user-gravatar32"> <a href="/users/17082/ryan-tuck"><div class=""><img src="https://www.gravatar.com/avatar/57bb887b039eb0ca9f976210fe821a2a?s=32&d=identicon&r=PG" alt="" width="32" height="32"></div></a> </div> <div class="user-details"> <a href="/users/17082/ryan-tuck">Ryan Tuck</a><br> <span class="reputation-score" title="reputation score" dir="ltr">114</span><span title="5 bronze badges"><span class="badge3"></span><span class="badgecount">5</span></span> </div> </div> </div> </div> </div> <div class="question-summary" id="question-summary-80365"> <div class="statscontainer"> <div class="statsarrow"></div> <div class="stats"> <div class="vote"> <div class="votes"> <span class="vote-count-post "><strong>6</strong></span> <div class="viewcount">votes</div> </div> </div> <div class="status answered-accepted"> <strong>4</strong>answers </div> </div> <div class="views " title="88 views"> 88 views </div> </div> <div class="summary"> <h3><a href="/questions/80365/capacitor-inrush-current" class="question-hyperlink">Capacitor Inrush Current</a></h3> <div class="excerpt"> I have to filter a power control circuit and as usual I am using lots of capacitors in parallel. Some of these capacitors are Tantalum or Aluminium Polymer types, with ripple current ratings of 3 amps ... </div> <div class="tags t-capacitor t-inrush-current"> <a href="/questions/tagged/capacitor" class="post-tag" title="show questions tagged \'capacitor\'" rel="tag">capacitor</a> <a href="/questions/tagged/inrush-current" class="post-tag" title="show questions tagged \'inrush-current\'" rel="tag">inrush-current</a> </div> <div class="started fr"> <div class="user-info user-hover"> <div class="user-action-time"> asked <span title="2013-08-27 18:04:39Z" class="relativetime">16 hours ago</span> </div> <div class="user-gravatar32"> <a href="/users/15955/mfeinstein"><div class=""><img src="https://www.gravatar.com/avatar/86b9f964b2a1d7cc66a78a6199801f71?s=32&d=identicon&r=PG" alt="" width="32" height="32"></div></a> </div> <div class="user-details"> <a href="/users/15955/mfeinstein">mFeinstein</a><br> <span class="reputation-score" title="reputation score" dir="ltr">1,006</span><span title="11 bronze badges"><span class="badge3"></span><span class="badgecount">11</span></span> </div> </div> </div> </div> </div> <div class="question-summary" id="question-summary-80360"> <div class="statscontainer"> <div class="statsarrow"></div> <div class="stats"> <div class="vote"> <div class="votes"> <span class="vote-count-post "><strong>0</strong></span> <div class="viewcount">votes</div> </div> </div> <div class="status answered"> <strong>1</strong>answer </div> </div> <div class="views " title="28 views"> 28 views </div> </div> <div class="summary"> <h3><a href="/questions/80360/designing-adc-driver-circuit-using-ltc6406" class="question-hyperlink">Designing ADC driver circuit using LTC6406</a></h3> <div class="excerpt"> I am designing the front end(single ended to differential) for the ADC using LTC6406 to interface with the 20MSPS ADC. My input frequency is 140 MHz. Simulation Sch is shown below: L1, L2 and C1 are ... </div> <div class="tags t-circuit t-adc"> <a href="/questions/tagged/circuit" class="post-tag" title="show questions tagged \'circuit\'" rel="tag">circuit</a> <a href="/questions/tagged/adc" class="post-tag" title="show questions tagged \'adc\'" rel="tag">adc</a> </div> <div class="started fr"> <div class="user-info "> <div class="user-action-time"> asked <span title="2013-08-27 17:36:42Z" class="relativetime">17 hours ago</span> </div> <div class="user-gravatar32"> <a href="/users/25017/anand-kumar-rai"><div class="gravatar-wrapper-32"><img src="http://i.stack.imgur.com/v6adE.jpg?s=32&g=1" alt=""></div></a> </div> <div class="user-details"> <a href="/users/25017/anand-kumar-rai">Anand Kumar Rai</a><br> <span class="reputation-score" title="reputation score" dir="ltr">183</span><span title="1 silver badge"><span class="badge2"></span><span class="badgecount">1</span></span><span title="10 bronze badges"><span 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JavaScript enabled<img src="http://pixel.quantserve.com/pixel/p-c1rF4kxgLUzNc.gif" alt="" class="dno"></div> </noscript> <script type="text/javascript">var _gaq=_gaq||[];_gaq.push([\'_setAccount\',\'UA-5620270-24\']); _gaq.push([\'_setDomainName\',\'.stackexchange.com\']); _gaq.push([\'_trackPageview\']); var _qevents = _qevents || []; (function () { var ssl=\'https:\'==document.location.protocol, s=document.getElementsByTagName(\'script\')[0], ga=document.createElement(\'script\'); ga.type=\'text/javascript\'; ga.async=true; ga.src=(ssl?\'https://ssl\':\'http://www\')+\'.google-analytics.com/ga.js\'; s.parentNode.insertBefore(ga,s); var sc=document.createElement(\'script\'); sc.type=\'text/javascript\'; sc.async=true; sc.src=(ssl?\'https://secure\':\'http://edge\')+\'.quantserve.com/quant.js\'; s.parentNode.insertBefore(sc,s); })(); _qevents.push({ qacct: "p-c1rF4kxgLUzNc" }); </script> </body> </html>'; my $regex = qr/(?<code1><a href="\/questions\/\d+.+?">)(?<code2>.+)(?<code3><\/a)/p; if ( $str =~ /$regex/g ) { print "Whole match is ${^MATCH} and its start/end positions can be obtained via \$-[0] and \$+[0]\n"; # print "Capture Group 1 is $1 and its start/end positions can be obtained via \$-[1] and \$+[1]\n"; # print "Capture Group 2 is $2 ... and so on\n"; } # ${^POSTMATCH} and ${^PREMATCH} are also available with the use of '/p' # Named capture groups can be called via $+{name}

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 Perl, please visit: http://perldoc.perl.org/perlre.html