• Filter use when the data source contains user input data or unknown data.


• Validation is used to validate or restrict some user input.


• Filter use mainly for security purpose because we can not trust on external data such as :
  
  
  1. input data from a form.
  2. cookies.
  3. Web services data.
  4. Server variables.
  5. Database query results).

Functions	Description
filter_var()	Filters a single variable with a specific filter.
filter_var_array()	Filter more than one variables with the same or different filters.
filter_input	Receive one input variable and filter it.
filter_input_array	Receive more than one input variables and filter them with the same or different filters.

Example :

<?php
$int= 10000000123;

if(!filter_var($int, FILTER_VALIDATE_INT))
  {
  echo("Integer is not valid");
  }
else
  {
  echo("Integer is valid");
  }
?>

Output :

Integer is not valid

Validate Input

By using filter_input() function ,we can filter user-input.

Example :

<?php
if(!filter_has_var(INPUT_GET, "email-id"))
  {
  echo("Input type does not exist");
  }
else
  {
  if (!filter_input(INPUT_GET, "email-id", FILTER_VALIDATE_EMAIL))
    {
    echo "E-Mail id is not valid";
    }
  else
    {
    echo "E-Mail id is valid";
    }
  }
?>