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.

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.

function url_encode( s ) {
	return encodeURIComponent( s ).replace( /\%20/g, '+' ).replace( /!/g, '%21' ).replace( /'/g, '%27' ).replace( /\(/g, '%28' ).replace( /\)/g, '%29' ).replace( /\*/g, '%2A' ).replace( /\~/g, '%7E' );
}

This basically uses regular expressions to do a global replace on characters encodeURIComponent misses.

Another tiny trick that I liked is a JavaScript foreach loop. I use this regularly in PHP but its not exactly obvious in JavaScript.
Use the following code…

var some_array = new Array;
some_array['a'] = 1;
some_array['b'] = 2;
some_array['c'] = 3;
for ( var key in some_array ) {
  var value = some_array[key];
  console.log( 'Key: ' + key + ', Value: ' + value ); 
}
//outputs...
// Key: a, Value: 1
// Key: b, Value: 2
// Key: c, Value: 3

This is particularly handy with associative arrays like above.

Final ickle trick is a bit of code to remove the last character from a string. Use the JavaScript slice function and its easy peasy…

var some_string = '"102","123","45","583",';
some_string = some_string.slice(0, -1);

Why is this handy? Well I use loops to construct formatted stings with some delimiter, like the comma in the code above.
However the string usually ends up with the delimiter added on at the end. So I like to remove it at the end rather than checking if I should not append the delimiter with each iteration of the loop.
I think it is much tidier and it is probably quicker but I am open to correction.

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.

Starting with a couple of simple functions I use to validate email addresses (thanks WordPress core!) and URLs.

function is_url ( $url ) {
	return ( ! preg_match ( '/^(http|https|ftp):\/\/([A-Z0-9][A-Z0-9_-]*(?:\.[A-Z0-9][A-Z0-9_-]*)+):?(\d+)?\/?/i', $url ) ) ? FALSE : TRUE;
}

function is_email( $email ) {
	// Test for the minimum length the email can be
	if ( strlen( $email ) < 3 ) {
		return false;
	}

	// Test for an @ character after the first position
	if ( strpos( $email, '@', 1 ) === false ) {
		return false;
	}

	// Split out the local and domain parts
	list( $local, $domain ) = explode( '@', $email, 2 );

	// LOCAL PART
	// Test for invalid characters
	if ( !preg_match( '/^[a-zA-Z0-9!#$%&\'*+\/=?^_`{|}~\.-]+$/', $local ) ) {
		return false;
	}

	// DOMAIN PART
	// Test for sequences of periods
	if ( preg_match( '/\.{2,}/', $domain ) ) {
		return false;
	}

	// Test for leading and trailing periods and whitespace
	if ( trim( $domain, " \t\n\r\0\x0B." ) !== $domain ) {
		return false;
	}

	// Split the domain into subs
	$subs = explode( '.', $domain );

	// Assume the domain will have at least two subs
	if ( 2 > count( $subs ) ) {
		return false;
	}

	// Loop through each sub
	foreach ( $subs as $sub ) {
		// Test for leading and trailing hyphens and whitespace
		if ( trim( $sub, " \t\n\r\0\x0B-" ) !== $sub ) {
			return false;
		}

		// Test for invalid characters
		if ( !preg_match('/^[a-z0-9-]+$/i', $sub ) ) {
			return false;
		}
	}

	// Congratulations your email made it!
	return true;
}

Lastly and most recently, I wanted to parse a string of code to find an assignment value.
I came across a neat regex to help me parse out the values of these variables.

$code = "var string_variable = Superduper;
var digit_variable = 123456;";

function get_assignment_value( $needle, $haystack, $type = 'string' ) {
	if( $type == 'digit' )
		preg_match( '/.'.$needle.' = (?P<value>\d+)/', $haystack, $matches );
	else
		preg_match( '/.'.$needle.' = (?P<value>\w+)/', $haystack, $matches );
	
	if( empty( $matches[ 'value' ] ) )
		return false;

	if( $type == 'digit' )
		return (int) $matches[ 'value' ];
	
	return $matches[ 'value' ];
}

var_dump( get_assignment_value( 'string_variable', $code ) ); // string(10) "Superduper"
var_dump( get_assignment_value( 'digit_variable', $code, 'digit' ) ); // int(123456) 
var_dump( get_assignment_value( 'digit_variable', $code  ) ); // string(6) "123456" 

My main source of guidance on this voodoo here and their sometimes hard to find but useful reference.

Also, here is a good starter on building a regex.