When working with regular expressions, it can be difficult to understand why a particualar pattern is not working as you would expect.
The visual debug tool at debuggex.com makes it much easier to step through and actually visualize how a pattern is working or, as is often the case, not working.
Here is an overview of how it works.
I found this regex useful when parsing log files to find everything except the data I needed. I can select and delete everything I don’t need and I am left with the lines of data I can work with. Continue reading “Regex – Find everything except – Caret”
Found this super handy cheat sheet for regular expressions.
Regular Expressions Cheat Sheet
Also, this serves as a useful reminder when returning to regular expressions.
Continue reading “Regular Expressions Cheat Sheet & Practical Uses”
You may at some stage want to filter an online service based on IP address. In other words, you may want to block or grant access to a request based on their IP address. This can be handled in PHP by doing the following.
If you have the IP addresses, then it is trivial.
//First check IP address is valid
$request_ip = $_SERVER['REMOTE_ADDR'];
if ( !preg_match( "/^(([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]).){3}([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$/", $request_ip ) )
return false;
$blacklist = array(
'111.222.12.11',
'222.111.21.22',
'221.112.11.12'
);
//check that ip is not blacklisted
if ( in_array( $request_ip, $blacklist ) )
return false;
If you want to include a range of IP addresses, best to use a regular expression.
$blacklist_ip_range = array(
'/^122\.244\.(\d+)\.(\d+)/', //for IP address in the range 122.244.0.0 - 122.244.255.255
'/^123\.(\d+)\.(\d+)\.(\d+)/', //for IP address in the range 123.0.0.0 - 123.255.255.255
);
foreach( $blacklist_ip_range as $ip ) {
if( preg_match( $ip, $request_ip ) )
return false;
}
If you have a better solution, then please let me know.
I have come across some neat (if not mind blowing) tricks with JavaScript recently.
Firstly, I needed JavaScript code that copied PHP’s urlencode().
This function returns an encoded string where all non-alphanumeric characters except – _ . are replaced with a percent (%) sign followed by two hex digits and spaces encoded as plus (+) signs.
JavaScript has 2 functions to emulate urlencode(), but both fall short…
The escape function encodes all non-alphanumeric characters except * @ / + – _ .
The encodeURIComponent function encodes all non-alphanumeric characters except spaces and ! ‘ ( ) * ~
The winner for me though is encodeURIComponent as it encodes all UTF-8 characters while escape only encodes ISO Latin characters.
With this in hand, mozilla help provide a neat function.
Continue reading “JavaScript Tricks; URLEncode, Foreach and Remove last character”
First off, regular expressions are great.
They are a handy quick way to validate or parse data and you can use them in almost all languages. But of all things, I forget neat regex’s and in fairness they are a pita to recall as the syntax is plain nutty.
This is where it ends. I am going to reference all the neat regex’s in this blog as I come across them rather than rely on mother Google.
Continue reading “Regular Expressions”
magp.ie 