# PHP filter_input() Function

Complete PHP Filter Reference

## Definition and Usage

The filter_input() function gets external variables (like form input) and filters them.

This function is used to validate variables from insecure sources, such as user input.

This function can get input from several sources:

- INPUT_GET
- INPUT_POST
- INPUT_COOKIE
- INPUT_ENV
- INPUT_SERVER
- INPUT_SESSION (Not yet implemented)
- INPUT_REQUEST (Not yet implemented)

Returns the filtered data on success, FALSE on failure or NULL if the "variable" parameter is not set.

## Syntax

filter_input(input_type, variable, filter, options)

Parameter | Description
--- | ---
input_type | Required. Specifies the input type. See possible types in list above
variable | Required. Specifies the variable to filter
filter | Optional. Specifies the ID of the filter to use. Default is FILTER_SANITIZE_STRING. Check the Complete PHP Filter Reference for possible filters A filter ID can be an ID name (like FILTER_VALIDATE_EMAIL) or an ID number (like 274)
options | Optional. Specifies an associative array of flags/options or a single flag/option. Check each filter for possible options and flags

## Example

In this example we use the filter_input() function to filter a POST variable. The received POST variable is a valid e-mail address:

<?php
if (!filter_input(INPUT_POST, 'email', FILTER_VALIDATE_EMAIL))
{
echo "E-Mail is not valid";
}
else
{
echo "E-Mail is valid";
}
?>

The output of the code should be:

E-Mail is valid

Complete PHP Filter Reference

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