php man page for filter_var

FILTER_VAR(3)								 1							     FILTER_VAR(3)

filter_var - Filters a variable with a specified filter

SYNOPSIS
       mixed filter_var (mixed	$variable, [int  $filter = FILTER_DEFAULT], [mixed  $options])

DESCRIPTION
PARAMETERS
	      o $variable
		- Value to filter.

	      o $filter
		-  The ID of the filter to apply. The "Types of filters" manual page lists the available filters.  If omitted, FILTER_DEFAULT will
		be used, which is equivalent to FILTER_UNSAFE_RAW. This will result in no filtering taking place by default.

	      o $options
		- Associative array of options or bitwise disjunction of flags. If filter accepts options, flags can be provided in "flags"  field
		of  array.  For the "callback" filter, callable type should be passed. The callback must accept one argument, the value to be fil-
		tered, and return the value after filtering/sanitizing it.

	      <?php
	      // for filters that accept options, use this format
	      $options = array(
		  'options' => array(
		      'default' => 3, // value to return if the filter fails
		      // other options here
		      'min_range' => 0
		  ),
		  'flags' => FILTER_FLAG_ALLOW_OCTAL,
	      );
	      $var = filter_var('0755', FILTER_VALIDATE_INT, $options);

	      // for filter that only accept flags, you can pass them directly
	      $var = filter_var('oops', FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE);

	      // for filter that only accept flags, you can also pass as an array
	      $var = filter_var('oops', FILTER_VALIDATE_BOOLEAN,
				array('flags' => FILTER_NULL_ON_FAILURE));

	      // callback validate filter
	      function foo($value)
	      {
		  // Expected format: Surname, GivenNames
		  if (strpos($value, ", ") === false) return false;
		  list($surname, $givennames) = explode(", ", $value, 2);
		  $empty = (empty($surname) || empty($givennames));
		  $notstrings = (!is_string($surname) || !is_string($givennames));
		  if ($empty || $notstrings) {
		      return false;
		  } else {
		      return $value;
		  }
	      }
	      $var = filter_var('Doe, Jane Sue', FILTER_CALLBACK, array('options' => 'foo'));
	      ?>

RETURN VALUES
	Returns the filtered data, or FALSE if the filter fails.

EXAMPLES
       Example #1

	      A filter_var(3) example

	      <?php
	      var_dump(filter_var('bob@example.com', FILTER_VALIDATE_EMAIL));
	      var_dump(filter_var('http://example.com', FILTER_VALIDATE_URL, FILTER_FLAG_PATH_REQUIRED));
	      ?>

	      The above example will output:

	      string(15) "bob@example.com"
	      bool(false)

SEE ALSO
       filter_var_array(3), filter_input(3), filter_input_array(3), "Types of filters", information about the callback type.

PHP Documentation Group 													     FILTER_VAR(3)