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

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Release： 2023-04-03 14:54:02
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This article introduces to you a summary of the four security filtering functions in PHP (with code). It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

1. Stripslashes() function

The main function of stripslashes() is to delete backslashes 

<?php
echo stripslashes("Who\&#39;s Bill Gates?");
?>
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Output result: 

Who&#39;s Bill Gates?
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2. htmlentities() function

htmlentities() converts characters into HTML entities 

<?php
$str = "<? W3S?h????>";
echo htmlentities($str);
?>
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The HTML output of the above code is as follows (view source code): 

<!DOCTYPE html>
<html>
<body>
<© W3Sçh°°¦§>
</body>
</html>
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Browser output of the above code:

<? W3S?h????>
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3, htmlspecialchars() function

Convert the predefined characters "<" (less than) and " >" (greater than) converted to HTML entity:

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

<!DOCTYPE html>
<html>
<body>
This is some <b>bold</b> text.
</body>
</html>
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The browser output of the above code:

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

Strips the HTML tags in the string:

strip_tags() function strips the HTML, XML and PHP in the string Label.

Comments: This function always strips HTML comments. This cannot be changed via the allow parameter.

Note: This function is binary safe. 

<?php
echo strip_tags("Hello <b>world!</b>");
?>
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Hello world!
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Recommended related articles:

Summary of methods for extracting numbers from strings in php (code)

echo statement in PHP5 and What is the difference between print statements

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