Check if a string is numeric or not.

<?php
function validate_number($string)
{
if(is_numeric($string))
	{
	return true;
	}
	else
	{
	return false;
	}
}
?>

This function checks if an email address is valid or not. For example it is very useful if you have to validate a HTML form where someone should enter a real email address.

function ValidateEmail($email)
{
/*
(Name) Letters, Numbers, Dots, Hyphens and Underscores
(@ sign)
(Domain) (with possible subdomain(s) ).
Contains only letters, numbers, dots and hyphens (up to 255 characters)
(. sign)
(Extension) Letters only (up to 10 (can be increased in the future) characters)
*/

$regex = '/([a-z0-9_.-]+)'. # name

'@'. # at

'([a-z0-9.-]+){2,255}'. # domain & possibly subdomains

'.'. # period

'([a-z]+){2,10}/i'; # domain extension 

if($email == '') {
	return false;
}
else {
$eregi = preg_replace($regex, '', $email);
}

return empty($eregi) ? true : false;
}

$email = 'name@domain.com'; 

// will return true, since it matches the regex

if(ValidateEmail($email))
{
echo ''.$email.' is a valid e-mail address.';
}
else
{
echo ''.$email.' is not a valid e-mail address.';
}

Using this piece of code you will get the filename of the currently executing script without containing the full path to it.

For instance if $_SERVER['PHP_SELF'] is equal with /public_html/web/login.php our code will return only login.php

$self = basename($_SERVER['PHP_SELF']);

This function removes empty values from an array. This is useful if you’re working with dynamical arrays (for instance data harvested from a web site).

<?php
/*
Credits: Bit Repository
URL: http://www.bitrepository.com/web-programming/php/remove-empty-values-from-an-array.html
*/
function remove_array_empty_values($array, $remove_null_number = true)
{
	$new_array = array();

	$null_exceptions = array();

	foreach ($array as $key => $value)
	{
		$value = trim($value);

        if($remove_null_number)
		{
	        $null_exceptions[] = '0';
		}

        if(!in_array($value, $null_exceptions) && $value != "")
		{
            $new_array[] = $value;
        }
    }
    return $new_array;
}
?>

Example of usage:

$array = array("white", "yellow", 0, "green", " ", "navy");

$remove_null_number = true;
$new_array = remove_array_empty_values($array, $remove_null_number);

echo '<pre>'; print_r($new_array); echo '</pre>';

The new array will look like this:

Array
(
    [0] => white
    [1] => yellow
    [2] => green
    [3] => navy
)

NOTE: If you wish to keep the null number (0) then set the variable $remove_null_number to false.

This function will redirect the visitor to a specific location.

<?php
function go($location)
{
header("Location: ".$location);
exit;
}

// Location
$location = 'http://www.google.com/';

// Redirect the visitor
go($location);
?>