What is a PHP Filter?

[Beter 2 Burn Out]

Hi friends,
I have done some basic things in coding of PHP. You can say that I have used the PHP to some extent but I am not an expert in that.!! Last time your help was really grateful. So thought that this time also I should ask the doubt to you guys.!! Now I am stuck in the filters that are used in PHP. Please explain me what are PHP Filters.?? How they are used in PHP.? Expecting the same help as last time.!

[MELTRONICS]

Generally we use the term filter if we want to validate or verify something. Similarly, a PHP filter is used to validate and filter data coming from insecure sources. If you want to do the testing, you can validate and filter user input or custom data which is an important part of any web application. For making the data easier and faster, the PHP filter extension is designed. If you are using the PHP filter core module, that will add the ability to include PHP code in posts. Users with the proper permission may include custom PHP code within a page of the site, through the PHP filter.

[Deabelos]

If you are not new to the programming language then you should know that almost all web applications depend on external input. By using filters you can be sure your application gets the correct input type. The thing that you should keep in mind is that, you should always filter all external data. You can say that input filtering is one of the most important application security issues. An external input is the input that comes from a user or another application.

[kyosang]

If you want to filter a variable in your coding, you would have to use one of the following filter functions :

• filter_var() - This function is used to filters a single variable with a specified filter.
• filter_var_array() - This function is useful for filtering several variables with the same or different filters.
• filter_input - This function is used to get one input variable and filter it.
• filter_input_array - By using this function you can get several input variables and filter them with the same or different filters.

[MindSpace]

If you need to validate an integer using the filter_var() function, you can use the following code which explains the same thing :

<?php
$int = 234;

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