Articles:

• Search and replace across files using perl (23469)
• Reading command line arguments from perl (29242)
• How do I get a file's date / timestamp in perl? (21920)
• perl code to generate a time stamp for a unique file name (13728)
• Greating GIF, JPEG or PNG images with perl (7074)
• Regular expressions over multiple lines (15488)
• Special characters in regular expressions (8628)
• Trim blank space at the beginning and end of a string (7634)
• Check if a user name contains non-alphanumeric characters (5897)
• Embedding perl into HTML files like JSP or php (3981)
• Code snippets: parsing GET or POST data (4835)
• Temporarily turn off warnings in perl (older version) (4103)
• What kind of environment variables does a web context provide? (3226)
• Size of a perl associative array (hash) (7037)
• How can a perl script automate HTML form transmissions? (6363)
• Send an email from my perl script (5076)
• How to delete entries from a hash (associative array) in perl (4458)
• Calculate the differece between two dates (3945)
• perl command line options (3938)
• Force long strings to break up for better formatting (3795)
• Capitalize all the words in a string? (3594)
• How to test perl scripts offline (3177)
• How can I download a file via http? (2939)
• Determine the day of the year (2930)
• Have a perl script log in and retrieve some data (2872)
• How do I convert bits into ints? (2862)
• Generating a random number (2838)
• Obtaining the time and time in different formats (2601)
• Measure how long it takes to generate a web page with perl (2560)
• Some ideas for more web security with perl scripts (2551)
• Using octal data (2482)
• Introduction to classes and objects in perl (2413)
• Why should we switch from perl 5.6 to perl 5.8? (2376)
• Calculate the optimal maximum value for a y axis in a chart (1663)

• Perl Documentation
• Rex Swain's Perl Reference

Check if a user name contains non-alphanumeric characters Question: On my web site, a user may put in a desired user name and I have to check that it only contains letters, digits, or the @ and . characters. How can I do that with a regular expression (regex)? Answer: The allowed characters are described as A-Za-z0-9. That are the intervals A-Z, a-z and 0-9. You can also substitute 0-9 with d (digit). To check for the undesired character, use the ^ operator in front of it as shown below: if ($username =~ /([^A-Za-z0-9@.])/) { print "Problem in user name with '$1'"; }