A brief introduction to htmlspecialchars, strip_tags, and addslashes functions in php

In web program development, htmlspecialchars, strip_tags, and addslashes functions are the most common. This article will introduce these three functions respectively.

1.strip_tags() function

strip_tags() function removes HTML, XML and PHP tags from strings.

Example

<?php
$name="Hello <b>world!</b>";
$tags=strip_tags($name);
echo $tags;                        
?>

2.htmlspecialchars() function

htmlspecialchars() function converts predefined characters into HTML entity.

Specifically, this function will convert the following characters:

• & (and) into &

• " (double Quotation marks) is converted to "

• < (less than) is converted to <

• > (greater than) is converted to >

Example

<?php
$str = "This is some <b>bold</b> text.";
echo htmlspecialchars($str);
?>

3.htmlentities() function

Maybe you are still regretting that htmlspecialchars can only handle 4 html tags, so don't regret it now, htmlentities convert all characters. It’s not unpowerful

Example

<?php
$str = "<? PHP?h????>";
echo htmlentities($str);
?>

4. The functions stripslashes and addslashes are a pair. addslashes uses backslashes to quote strings, and stripslashes is Restore the string referenced by addslashes.

This function is generally a necessary step that needs to be processed before database query. This string has a backslash before certain characters for the purpose of database query statements, etc. These characters are single quotes ('), double quotes ("), backslash (/) and NUL (NULL character).

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