Regular Expressions - Revision history

Shane: Adding Regex XKCD

2014-01-11T11:53:05Z

Adding Regex XKCD

2013-07-03T21:38:10Z

Python

2013-07-03T21:37:13Z

Python

2013-07-03T21:32:15Z

Python

2013-04-01T10:11:57Z

JavaScript

2013-04-01T10:08:57Z

Using Regular Expressions in Your Workflow

2013-04-01T10:08:25Z

Using Regular Expressions in Programming Languages

2013-04-01T09:39:28Z

Using Regular Expressions in Programming Languages

2013-04-01T08:58:29Z

Groups

2013-03-27T05:02:31Z

JavaScript: DoctypeTV

← Older revision		Revision as of 11:53, 11 January 2014
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	This guide serves as an introduction to regular expressions. However, there is enough to discuss about them that regular expressions could be their ''own class''. We will only be scratching the surface so that you can get up and running with regular expressions and start to use them in your projects.		This guide serves as an introduction to regular expressions. However, there is enough to discuss about them that regular expressions could be their ''own class''. We will only be scratching the surface so that you can get up and running with regular expressions and start to use them in your projects.
		+
		+	{{XKCD
		+	\|name=regex_golf
		+	\|id=1313
		+	}}

	== Testing Regular Expressions ==		== Testing Regular Expressions ==

@@ Line 331: / Line 331: @@
 </source>
-In Python if you want to use the \b in a regex string (without declaring the string as raw) you need to use the \\b instead of \b . Consider the examples below, the first uses the raw input parameter, the second does not.
+In Python if you want to use the \b in a regex string (without declaring the string as raw) you need to use the \\b instead of \b . Consider the examples below, which provide the same output, the first uses the raw input parameter, the second does not.
 <source lang="python">

@@ Line 336: / Line 336: @@
 import re
-re.search(r"\bhello world\b","hello world").group()
+re.match(r"\bhello world\b","hello world").group()
-re.search("\\bhello world\\b","hello world").group()
+re.match("\\bhello world\\b","hello world").group()
 </source>

@@ Line 329: / Line 329: @@
 print(find_all_email_domains("sam@bbc.co.uk, julie@amazon.com, rick@wustl.edu"))
 # ['bbc.co.uk', 'amazon.com', 'wustl.edu']
 </source>

@@ Line 346: / Line 346: @@
 alert(/^\d+$/.test("123")); // true
 </source>
 {{DoctypeTV
@@ Line 352: / Line 354: @@
 |desc=Regular Expressions in JavaScript Part 2.
 }}
 <source lang="javascript">

← Older revision		Revision as of 10:08, 1 April 2013
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	You can also do regular expression '''find and replace''' in Komodo. You can use groups, too: in the "Replace with" box, a '''\1''' will insert your first group, a '''\2''' will insert your second group, and so on. Nifty!		You can also do regular expression '''find and replace''' in Komodo. You can use groups, too: in the "Replace with" box, a '''\1''' will insert your first group, a '''\2''' will insert your second group, and so on. Nifty!
		+
		+	[[Category:Module 4]]

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 |desc=Basics of Regular Expressions.  Uses JavaScript as the language of focus.
 }}
 {{DoctypeTV
@@ Line 344: / Line 352: @@
 |desc=Regular Expressions in JavaScript Part 2.
 }}
 {{DoctypeTV
@@ Line 350: / Line 372: @@
 |desc=Regular Expressions in JavaScript Part 3.
 }}
 == Using Regular Expressions in Your Workflow ==

@@ Line 270: / Line 270: @@
 === PHP ===
-The magic function in PHP is '''preg_match($regex, $str, $matches)''', where ''$regex'' is the regular expression, ''$str'' is the string to test, and ''$matches'' is an extra argument which will be modified to contain the matches array.
+The magic function in PHP is '''preg_match($regex, $str, $matches)''', where ''$regex'' is the regular expression, ''$str'' is the string to test, and ''$matches'' is an extra argument which will be modified to contain the matches array.  By convention, the regular expression itself must be surrounded in forward slashes.
 <source lang="PHP">
 function domain_from_email($str){
-	if(preg_match("/^[\w\-\+\.]+@([\w\-]+(?:\.[\w]{2,4})+)$/", $str, $matches)){
+	$email_regex = "/^[\w!#$%&'*+\/=?^_`{|}~-]+@([\w\-]+(?:\.[\w\-]+)+)$/";
 		return $matches[1];
 	} else return false;
+}
 </source>
 === Python ===
 === JavaScript ===

@@ Line 216: / Line 216: @@
 One use of regular expressions is when you want to extract information of a known format out of a string.  This is when ''groups'' come into play.
-'' under construction ''
+For example, consider the phone number expression from before.  Suppose we test it against the phone number "123-456-7890":
 == Using Regular Expressions in Programming Languages ==

@@ Line 244: / Line 244: @@
 |time=3m58s
 |desc=Basics of Regular Expressions.  Uses JavaScript as the language of focus.
 }}