class string
{
	/**
	 * Checks to see if string is only alphabetic
	 *
	 * @param string $value
	 * @param boolean $ignore_spaces
	 * @return boolean
	 */
 
	static function isAlpha($value, $ignore_spaces = false)
	{
		if (!isset($value))
		{
			return false;
		}
 
		if ($ignore_spaces)
		{
			$value = str_replace(" ", "", $value);
		}
 
		return ctype_alpha($value);
	}
 
	/**
	 * Checks to see if string only contains letters and numbers
	 *
	 * @param string $value
	 * @param boolean $ignore_spaces
	 * @return boolean
	 */
 
	static function isAlphaNum($value, $ignore_spaces = false)
	{
		if (!isset($value))
		{
			return false;
		}
 
		if ($ignore_spaces)
		{
			$value = str_replace(" ", "", $value);
		}
 
		return ctype_alnum($value);
	}
 
 
 
	/**
	 * Checks to see if a string is numeric
	 *
	 * @param string $value
	 * @param boolean $ignore_spaces
	 * @return boolean
	 */
 
	static function isNumeric($value, $ignore_spaces = false)
	{
		if (!isset($value))
		{
			return false;
		}
 
		if ($ignore_spaces)
		{
			$value = str_replace(" ", "", $value);
		}
 
		return ctype_digit($value);
	}
 
	/**
	 * Checks to see if string is a valid phone number
	 *
	 * @param string $value
	 * @return boolean
	 */
 
	static function isPhone($value)
	{
		if (!isset($value))
		{
			return false;
		}
 
		if(ereg("^[0-9]{3}-[0-9]{3}-[0-9]{4}$", $value) || 
		ereg("^\([0-9]{3}\)-[0-9]{3}-[0-9]{4}$", $value) ||
		ereg("^\([0-9]{3}\)[0-9]{3}-[0-9]{4}$", $value) ||
		ereg("^\([0-9]{3}\) [0-9]{3}-[0-9]{4}$", $value) ||
		ereg("^[0-9]{3}[0-9]{3}[0-9]{4}$", $value) ||
		ereg("^[0-9]{3} [0-9]{3} [0-9]{4}$", $value)
		) 
 
		{
			return true;
		}
		else 
		{
			return false;
		}
	}
 
	/**
	 * Checks to see if a string is an email
	 *
	 * @param string $value
	 * @param boolean $check_domain
	 * @return boolean
	 */
 
	public static function isEmail($value, $check_domain = false)
	{
		if (!isset($value))
		{
			return false;
		}
 
		if(eregi("^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$", $value)) 
		{
			if ($check_domain == true)
			{
				list($userName, $mailDomain) = split("@", $value);
 
				if (checkdnsrr($mailDomain, "MX")) {
				 	return true;
				}
				else 
				{
					return false;
				}
			}
		  return true;
		}
		else 
		{
		  return false;
		}
	}
 
	/**
	 * Checks to see if a string is a valid zip code
	 *
	 * @param string $value
	 * @param boolean $extended
	 * @return boolean
	 */
 
	static function isZip($value, $extended = false)
	{
		if (!isset($value))
		{
			return false;
		}
 
 
		if (!$extended)
		{
		  if(ereg("^[0-9]{5}$", $value))
		  {  
		  	return true;
		  }
		  else
		  {
		    return false;
		  }
		}
		else
		{
			if(ereg("^[0-9]{5}$", $value) || ereg("^[0-9]{5}-[0-9]{4}$", $value))
			  {  
			  	return true;
			  }
			  else
			  {
			    return false;
			  }
		}
	}
 
	/**
	 * Validates credit card number
	 *
	 * @param string $value
	 * @return boolean
	 */
 
	static function isCreditCard($value)
	{
		if (!isset($value))
		{
			return false;
		}
		if (ereg("(^(4|5)\d{3}-?\d{4}-?\d{4}-?\d{4}|(4|5)\d{15})|(^(6011)-?\d{4}-?\d{4}-?\d{4}|(6011)-?\d{12})|(^((3\d{3}))-\d{6}-\d{5}|^((3\d{14})))", $value))
		{
			return true;
		}
		else
		{
			return false;
		}
	}
 
	/**
	 * Strips html out of a string
	 *
	 * @param string $value
	 */
 
	static function stripHTML(&$value)
	{
		if (!isset($value))
		{
			exit;
		}
 
		$breaks[] = "<br>";
		$breaks[] = "<br />";
		$search = array('@<script[^>]*?>.*?</script>@si',  // Strip out javascript
               '@<style[^>]*?>.*?</style>@siU'    // Strip style tags properly
				);
 
		$value = preg_replace($search, '', $value);
		$value = str_ireplace($breaks, "\r\n", $value);
		$value = trim($value);
		$value = strip_tags($value);
		$value = html_entity_decode($value, ENT_QUOTES);
		$value = addslashes($value);
	}
 
	static function cleanHTML(&$value)
	{
		$search = array('@<script[^>]*?>.*?</script>@si',  // Strip out javascript
               '@<style[^>]*?>.*?</style>@siU'    // Strip style tags properly
				);
		$value = preg_replace($search, '', $value);
		$value = htmlentities($value);
	}
}