Summary of four types of security filtering functions in PHP (with code)

This article introduces you to the content of PHP four security filter function summary (with code), there is a certain reference value, the need for friends can refer to, I hope to help you.

1. Stripslashes () function

Stripslashes () The main function is to remove the backslash

<?phpecho stripslashes ("Who\ 's Bill Gates?");? >

Output Result:

Who ' s Bill Gates?

2. Htmlentities () function

Htmlentities () converts a character to an HTML entity

<?php$str = "<?" W3s?h???? > Echo htmlentities ($str);? >

The HTML output of the above code is as follows (see source code):

<! DOCTYPE html>
The browser output of the above code:

<? W3s?h???? >
3. Htmlspecialchars () function

Convert pre-defined characters "<" (less than) and ">" (greater than) to HTML entities:

<?php$str = "This is some <b>bold</b> text."; echo Htmlspecialchars ($STR);? >
The HTML output of the above code is as follows (see source code):

<! DOCTYPE Html>
The browser output of the above code:

This is some <b>bold</b> text.
4. Strip_tags () function

Peel the HTML tags from the string:

The Strip_tags () function strips the HTML, XML, and PHP tags from the string.

Note: This function always strips HTML comments. This cannot be  changed by the Allow parameter.

Note: This function is binary safe.

<?phpecho strip_tags ("Hello <b>world!</b>");? >
Hello world!
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