When to use PHP filter_input()


For a long time I use $_POST[] in my applications, however I have seen that some colleagues use filter_input() instead of $_POST[] . I've already opened the PHP documentation , but I confess that I couldn't quite understand its use. My questions are:

  1. What is the use of filter_input() ;
  2. If it is valid to change $_POST[] by filter_input() ;
  3. When should we use filter_input() ;

I saw that in the documentation, it highlights FILTER_SANITIZE_SPECIAL_CHARS , FILTER_SANITIZE_ENCODED , FILTER_DEFAULT and FILTER_VALIDATE_EMAIL . This last use to validate email:

$email = filter_input(INPUT_POST,"EmailVerificar",FILTER_VALIDATE_EMAIL);

But only this one that I understood the use.


So my dear, first good morning!

As you've already visited PHP documentation , I'm just going to give you a quick brushstroke for each item you've cited in the thread.

1.- The filter_input() can be said to be a combination of variables already known by us PHP programmers ($_POST, $_GET and others) into a single function and "optionally filters it (as mentioned in the documentation)".

2.- Yes it is really valid for you to exchange a $_POST for one let's suppose filter_input(INPUT_POST, 'username', FILTER_SANITIZE_STRING) or filter_input(INPUT_POST, 'username', FILTER_SPECIAL_CHARS) (It is just a very basic example of how it could to be used)

3.- It could be used in too many occasions, like for example in a $_GET and checking if the $_GET is numeric… $foo = filter_input(INPUT_GET, 'foo', FILTER_SANITIZE_NUMBER_INT);

But we have a but if the index doesn't exist… On this occasion:

$foo = filter_var($_GET['foo'], FILTER_SANITIZE_NUMBER_INT);

Returns an empty string "" and generates:

Notice: Undefined index: foo

Our current one, following the documentation parameters, will only return a NULL result:

$foo = filter_input(INPUT_GET, 'foo', FILTER_SANITIZE_NUMBER_INT);

Returns only:


But basically the answer is: YES , you can do a simple switch from your $_POST to filter_input() . (I even use it in my projects! Kkk)

Just adding up the information (Thanks to @Fox.11 for posting) in case there are too many questions about the two filter options.


Used to clear variables:



Used to validate variables:


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