How to block keywords in php? Brief analysis of two methods

PHP is a server-side scripting language widely used for web development. In modern web development, developers often need to deal with large amounts of user data. Sometimes, these users may submit malicious text, such as attack code, advertisements, spam, etc.

In order to protect our web applications from these malicious texts, we need to be able to block some keywords. This article will introduce two ways to block keywords in PHP.

Method 1: Use PHP’s built-in functions

PHP has built-in functions to process strings, regular expressions, HTML, etc. One of the string processing functions is very useful, which is the str_replace() function. This function finds a substring in a string and replaces it with another string.

The following is an example of using the str_replace() function to block malicious text keywords submitted by users:

<?php
$bad_words = array(&#39;攻击&#39;, &#39;广告&#39;, &#39;垃圾邮件&#39;);
$text = &#39;这是一段包含攻击、广告和垃圾邮件的文本。&#39;;
$filtered_text = str_replace($bad_words, &#39;*&#39;, $text);
echo $filtered_text;
?>

In the above code, we used The str_replace() function replaces text containing keywords with a * character.

Method 2: Use regular expressions

If we need to block more complex text formats, such as URLs, HTML codes, JavaScript, etc. , we can use the regular expressions provided by PHP.

The following is an example of using regular expressions to match malicious URLs:

<?php
$text = &#39;这是一个包含恶意链接的文本，例如：http://www.example.com/attack?param=val&#39;;
$filtered_text = preg_replace(&#39;/http:\/\/[a-z0-9.]+[a-z]{2,}\/[a-z]+/i&#39;, &#39;*&#39;, $text);
echo $filtered_text;
?>

In the above code, we use PHP’s built-in preg_replace() function and a Regular expression to match text containing malicious URLs. Regular expression /http:\/\/[a-z0-9.] [a-z]{2,}\/[a-z] /i can match http://## It starts with #, followed by a domain name containing only a-z, 0-9 and ., followed by a URL containing only a-z path name.

Summary

In this article, we introduced two ways to block keywords in PHP. The first method is to use PHP's built-in string processing function

str_replace() to find and replace strings containing keywords. The second method is to use regular expressions to match more complex text formats. No matter which method is used, malicious text can be effectively blocked, thus protecting our web applications from attacks.

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