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Add lab "regex0" (#459)
Some learners may skip this, but let's give a simple introduction for those who have never seen regexes. Signed-off-by: David A. Wheeler <[email protected]>
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‎docs/labs/README.md

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* [hello](hello.html) - simple "Hello, world!" demo
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* [input1](input1.html) - input validation (simple types)
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* [regex0](regex0.html) - regular expressions (regexes) - introduction
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* [regex1](regex1.html) - regular expressions (regexes)
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* [input2](input2.html) - input validation (more complex situations)
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* [csp1](csp1.html) - Content Security Policy (CSP)
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* Input Validation: A Few Simple Data Types - [input1](input1.html)
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* Sidequest: Text, Unicode, and Locales
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* Validating Text
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* Introduction to Regular Expressions
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* Introduction to Regular Expressions - [regex0](regex0.html)
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* Using Regular Expressions for Text Input Validation - [regex1](regex1.html), [input2](input2.html)
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* Countering ReDoS Attacks on Regular Expressions - PLANNED-2
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* Input Validation: Beyond Numbers and Text

‎docs/labs/regex0.html

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<!DOCTYPE html>
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<html>
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<head>
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<meta http-equiv="X-UA-Compatible" content="IE=edge">
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<meta name="viewport" content="width=device-width, initial-scale=1">
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<link rel="stylesheet" href="https://best.openssf.org/assets/css/style.css">
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<link rel="stylesheet" href="checker.css">
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<script src="js-yaml.min.js"></script>
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<script src="checker.js"></script>
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<link rel="license" href="https://creativecommons.org/licenses/by/4.0/">
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<!-- See create_labs.md for how to create your own lab! -->
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<!-- Sample expected answer -->
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<script id="expected0" type="plain/text">
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cat
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</script>
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<!-- Full pattern of correct answer -->
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<script id="correct0" type="plain/text">
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cat
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</script>
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<!-- Sample expected answer -->
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<script id="expected1" type="plain/text">
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ABBBB
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</script>
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<!-- Full pattern of correct answer -->
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<script id="correct1" type="plain/text">
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A(\+|A\*)
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B(\+|B\*)
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</script>
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<script id="info" type="application/yaml">
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---
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hints:
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- present: |-
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^$
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text: You need to enter a pattern.
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- present: |-
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^\^
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text: We are looking for 'cat' anywhere, not just the beginning,
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in this exercise.
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- absent: |-
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c
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text: If you are searching for "cat" you need to look for a "c"
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examples:
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- - "x"
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- absent: |-
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cat
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text: The pattern "cat" is needed to search for "cat".
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- absent: |-
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A
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index: 1
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text: You need to mention A.
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- absent: |-
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B
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index: 1
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text: You need to mention B.
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- absent: |-
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A(\+|A\*)
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index: 1
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text: Use "A+" to indicate "one or more A". You could also write "AA*".
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- absent: |-
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B(\+|B\*)
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index: 1
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text: Use "B+" to indicate "one or more B". You could also write "BB*".
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# successes:
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# - - " query ( 'id' ) . isInt ( {min: 1 , max: 9999 } ) ,"
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# - - " query ( `id` ) . isInt ( {min: 1 , max: 9_999 } ) , "
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# - - 'query ( "id" ) . isInt ( {min: 1 , max: 9_999 } ) ,'
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# failures:
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# - - " query,"
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# - - 'query(''id'').isint({min: 1, max: 9999})'
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# - - 'query(''id'').isInt({min: 1, max: 9999})'
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#
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# Remove all whitespace, so we can make our patterns easier to read
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#
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preprocessing:
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-
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- |-
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\s*
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- ""
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# -
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# - |-
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# (\\s\*)?\s+(\\s\*)?
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# - "\\s*"
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# debug: true
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</script>
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<!--
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-->
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</head>
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<body>
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<!-- For GitHub Pages formatting: -->
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<div class="container-lg px-3 my-5 markdown-body">
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<h1>Lab Exercise regex0</h1>
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<p>
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This is a lab exercise on developing secure software.
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For more information, see the <a href="introduction.html" target="_blank">introduction to
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the labs</a>.
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<p>
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<h2>Goal</h2>
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<p>
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<b>Learn how to create simple regular expressions.</b>
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<p>
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<h2>Background</h2>
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<p>
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Regular expressions (regexes) are a widely-used notation for
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expressing text patterns.
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We will later see how to use regexes to validate input.
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<p>
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Different regex languages have slightly different notations,
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but they have much in common. Here are some basic rules for regex
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notations:
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<ol>
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<li>The most trivial rule is that a letter or digit matches itself. That is, the regex “<tt>d</tt>” matches the letter “<tt>d</tt>”. Most implementations use case-sensitive matches by default, and that is usually what you want.
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<li>Another rule is that square brackets surround a rule that specifies any of a number of characters. If the square brackets surround just alphanumerics, then the pattern matches any of them. So <tt>[brt]</tt> matches a single “<tt>b</tt>”, “<tt>r</tt>”, or “<tt>t</tt>”.
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Inside the brackets you can include
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ranges of symbols separated by dash ("-"), so
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<tt>[A-D]</tt> will match one character, which can be one A, one B, one C,
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or one D.
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You can do this more than once.
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For example,
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the term <tt>[A-Za-z]</tt> will match one character, which can be
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an uppercase Latin letter or a lowercase Latin letter.
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(This text assumes you're not using a long-obsolete character system
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like EBCDIC.)
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<li>If you follow a pattern with “<tt>&#42;</tt>”, that means
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“<i>0 or more times</i>”.
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In almost all regex implementations (except POSIX BRE),
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following a pattern with "<tt>+</tt>" means "<i>1 or more times</i>".
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So <tt>[A-D]*</tt> will match 0 or more letters as long as every letter
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is an A, B, C, or D.
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</ol>
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<p>
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<h2>Task Information</h2>
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<p>
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We're going to create some simple regular expressions (regexes)
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to look for certain patterns.
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<p>
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<h2>Interactive Lab (<span id="grade"></span>)</h2>
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<b>Please create regular expression (regex) patterns
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that meet the criteria below.</b>
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<h3>Part 1</h2>
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<p>
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Create a regular expression, for use in ECMAScript (JavaScript),
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that searches for the term "cat" anywhere in a string.
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<!--
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You can use this an example for new labs.
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For multi-line inputs, instead of <input id="attempt0" type="text" ...>, use
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<textarea id="attempt" rows="2" cols="65">...</textarea>
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-->
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<form id="lab1"><pre><code
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><input id="attempt0" type="text" size="60" spellcheck="false" value="">
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</code></pre>
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<button type="button" class="hintButton">Hint</button>
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<button type="button" class="resetButton">Reset</button>
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<button type="button" class="giveUpButton">Give up</button>
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</form>
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<h3>Part 2</h2>
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<p>
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Create a regular expression, for use in ECMAScript (JavaScript),
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that searches for one or more "A" followed by one or more "B".
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<!--
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You can use this an example for new labs.
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For multi-line inputs, instead of <input id="attempt0" type="text" ...>, use
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<textarea id="attempt" rows="2" cols="65">...</textarea>
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-->
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<form id="lab2">
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<pre><code
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><input id="attempt1" type="text" size="60" spellcheck="false" value="">
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</code></pre>
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<button type="button" class="hintButton">Hint</button>
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<button type="button" class="resetButton">Reset</button>
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<button type="button" class="giveUpButton">Give up</button>
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</form>
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<br><br>
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<p id="correctStamp" class="small">
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<textarea id="debugData" class="displayNone" rows="20" cols="65" readonly>
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</textarea>
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</div><!-- End GitHub pages formatting -->
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</body>
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</html>

‎docs/labs/regex1.html

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<p>
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<h2>Goal</h2>
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<p>
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<b>Learn how to create simple regular expressions.</b>
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<b>Learn how to create simple regular expressions for input validation.</b>
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<p>
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<h2>Background</h2>

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