Perl - Revision history

Alex: Removed Ubuntu support

2017-08-24T16:42:03Z

Removed Ubuntu support

Shane at 07:55, 8 April 2013

2013-04-08T07:55:17Z

Shane: categorizing

2013-02-24T23:23:59Z

categorizing

Juliad: Protected "Perl" ([edit=sysop] (indefinite) [move=sysop] (indefinite))

2010-07-16T20:33:21Z

Protected "Perl" ([edit=sysop] (indefinite) [move=sysop] (indefinite))

Taoju: /* Parsing HTML with Perl */

2009-10-30T18:35:39Z

Parsing HTML with Perl

Taoju: /* Defining Regular Expressions */

2009-10-30T18:26:09Z

Defining Regular Expressions

Taoju: /* Functions */

2009-10-30T17:40:36Z

Functions

Taoju: /* Regular Expressions */

2009-10-30T17:32:07Z

Regular Expressions

Taoju: /* Regular Expressions */

2009-10-30T17:31:47Z

Regular Expressions

Taoju: /* Using Regular Expressions */

2009-10-30T17:31:16Z

Using Regular Expressions

@@ Line 414: / Line 414: @@
 Perl modules are simply Perl libraries that provide new or enhanced functionality.  Although some modules are distributed as part of the core Perl distribution, most of them are written and maintained by other Perl users or developers who needed some specific functionality that was missing.  The [http://www.cpan.org CPAN] repository is the portal for finding and getting modules.  CPAN also contains manuals for the modules, most of which contain examples.  Generally speaking, the modules are all perl programs, although sometimes they require libraries from other languages.
-The typical location for perl modules is ''/usr/lib/perl/XXX'' where XXX is the version of perl.  For current Ubuntu installs, the perl version is 5.10, so the modules are in ''/usr/lib/perl/5.10/''.  You can define other locations by setting the ''PERL5LIB'' environmental variable.
+The typical location for perl modules is ''/usr/lib/perl/XXX'' where XXX is the version of perl.  You can define other locations by setting the ''PERL5LIB'' environmental variable.
   export PERL5LIB=directory1:directory2

← Older revision		Revision as of 07:55, 8 April 2013
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	Additional examples can be found in the Perl documentation for Tree Scanning [http://search.cpan.org/~sburke/HTML-Tree-3.18/lib/HTML/Tree/Scanning.pod here].		Additional examples can be found in the Perl documentation for Tree Scanning [http://search.cpan.org/~sburke/HTML-Tree-3.18/lib/HTML/Tree/Scanning.pod here].

		+	[[Category:Module 4]]
	[[Category:Former Content]]		[[Category:Former Content]]

← Older revision		Revision as of 23:23, 24 February 2013
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	Additional examples can be found in the Perl documentation for Tree Scanning [http://search.cpan.org/~sburke/HTML-Tree-3.18/lib/HTML/Tree/Scanning.pod here].		Additional examples can be found in the Perl documentation for Tree Scanning [http://search.cpan.org/~sburke/HTML-Tree-3.18/lib/HTML/Tree/Scanning.pod here].
		+
		+	[[Category:Former Content]]

@@ Line 702: / Line 702: @@
 </pre></code>
-However, these elements just give us the headlines, not the summaries. If you look at the BBC html document, the headlines are inside a ''<div>'' element.  The summaries are in the following ''<div>''.  So, we can reach those summaries by first moving to the parent of the hyperlink HTML::Element and then going to the next sibling of that parent:
+However, these elements just give us the headlines, not the summaries. If you look at the BBC html document, the headlines are inside a ''div'' element.  The summaries are in the following ''div''.  So, we can reach those summaries by first moving to the parent of the hyperlink HTML::Element and then going to the next sibling of that parent:
 <code><pre>

@@ Line 375: / Line 375: @@
 <code><pre>
-/[a-zA-Z0-9]+.pl/             # matches any .pl filename that consists of characters or digits
+/[a-zA-Z]+.pl/                # matches any .pl filename that consists of only alphabet characters
 /[a-z]+\s+\d*/                # matches a lowercase word, at least some space, and any number of digits
 </pre></code>

← Older revision	Revision as of 20:33, 16 July 2010
(No difference)

@@ Line 301: / Line 301: @@
   print "sum of 2+5=" . add(2,5) . "\n";
 </pre>
 </code>

@@ Line 309: / Line 309: @@
 A regular expression (or simply regex) can be thought of as a ''pattern'', composed of characters and symbols, which expresses what you want to search in a body of text. A regex is used in Perl functions such as string matching, search and replace, and splitting. In the following, we will first look at some typical ways of defining regex. Then we will give examples of how they are used in Perl functions.
 ==Defining Regular Expressions==
@@ Line 372: / Line 371: @@
 /[a-z]+\s+\d*/                # matches a lowercase word, at least some space, and any number of digits
 </pre></code>
 ==Using Regular Expressions==

@@ Line 309: / Line 309: @@
 A regular expression (or simply regex) can be thought of as a ''pattern'', composed of characters and symbols, which expresses what you want to search in a body of text. A regex is used in Perl functions such as string matching, search and replace, and splitting. In the following, we will first look at some typical ways of defining regex. Then we will give examples of how they are used in Perl functions.
 ==Defining Regular Expressions==
@@ Line 332: / Line 333: @@
 The backslash also works for non-printable ASCII characters, represented as escape sequences. Common examples are \s for a space, \t for a tab, \n for a newline, and \r for a carriage return.
 A '''character class''' allows a set of possible characters, rather than just a single character, to match at a particular point in a regex. Character classes are denoted by brackets [...] , with the set of characters to be possibly matched inside. A "-" can be used to specify range of characters. Here are some examples:
@@ Line 342: / Line 342: @@
 /[0-9a-fA-F]/                 # matches a hexadecimal digit
 </pre></code>
 Different character strings can be matched with the '''alternation''' metacharacter '|'. For example:
@@ Line 349: / Line 348: @@
 /cat|dog|bird/                # matches 'cat', or 'dog', or 'bird'
 </pre></code>
 We can '''group''' parts of a regex by enclosing them in parentheses '()'. For example:
@@ Line 356: / Line 354: @@
 /House(cat|keeper)/           # matches 'Housecat' or 'Housekeeper'
 </pre></code>
 One of the powerful features of regex is matching '''repetitions'''. The quantifier metacharacters ?, * , + , and {} allow us to determine the number of repeats of a portion of a regex we consider to be a match. Quantifiers are put immediately after the character, character class, or grouping that we want to specify. They have the following meanings:
@@ Line 375: / Line 372: @@
 /[a-z]+\s+\d*/                # matches a lowercase word, at least some space, and any number of digits
 </pre></code>
 ==Using Regular Expressions==
@@ Line 396: / Line 394: @@
 In the above example, the global modifier g asks Perl to search and replace all occurrences of the regex in the string. If there is a match, s/// returns the number of substitutions made, otherwise it returns false.
 Another use of regex is to '''split''' a string into a set of strings marked by delimiters, where the delimiters are specified by a given regex. This is done using the split function. For example, to split a string into words, do:

@@ Line 378: / Line 378: @@
 ==Using Regular Expressions==
-Regex is used almost any time when string matching is needed. To start, consider '''testing''' if a string contains the matching pattern (e.g., a regex). The operator "=~" associates the string with the regex match and produces a true value if the regex matched, or false if the regex did not match. Perl will always match at the earliest possible point in the string. For example:
+Regex is used almost any time when string matching is needed. To start, consider '''testing''' if a string contains the matching pattern (e.g., a regex). The operator =~ associates the string with the regex match and produces a true value if the regex matched, or false if the regex did not match. Perl will always match at the earliest possible point in the string. For example:
 <code><pre>
@@ Line 386: / Line 386: @@
 </pre></code>
-'''Search and replace''' is performed using the format "=~ s/regex/replacement/modifiers". The "replacement" is a Perl double quoted string that replaces in the string whatever is matched with the "regex". For example:
+'''Search and replace''' is performed using the format =~ s/regex/replacement/modifiers. The replacement is a Perl double quoted string that replaces in the string whatever is matched with the regex. For example:
 <code><pre>
@@ Line 395: / Line 395: @@
 </pre></code>
-In the above example, the global modifier "g" asks Perl to search and replace all occurrences of the regex in the string. If there is a match, "s///" returns the number of substitutions made, otherwise it returns false.
+In the above example, the global modifier g asks Perl to search and replace all occurrences of the regex in the string. If there is a match, s/// returns the number of substitutions made, otherwise it returns false.
-Another use of regex is to '''split''' a string into a set of strings marked by delimiters, where the delimiters are specified by a given regex. This is done using the "split" function. For example, to split a string into words, do:
+Another use of regex is to '''split''' a string into a set of strings marked by delimiters, where the delimiters are specified by a given regex. This is done using the split function. For example, to split a string into words, do:
 <code><pre>
@@ Line 407: / Line 407: @@
 </pre></code>
-As seen above, the "split" function returns the separated strings as an array. If the empty regex "//" is used, the string is split into individual characters.
+As seen above, the split function returns the separated strings as an array. If the empty regex // is used, the string is split into individual characters.
 =Perl Modules=