How to Implement Sensitive Word Filtering in PHP: Steps and Example Code

1. Introduction

In modern website development, sensitive word filtering is a crucial part of protecting user rights and ensuring content compliance. It helps prevent users from posting inappropriate content while reducing the legal risks companies might face due to user-generated harmful information. This article will explain how to implement sensitive word filtering in PHP.

2. Steps for Sensitive Word Filtering

2.1 Reading the Sensitive Word List

Before starting the filtering process, the first step is to read the list of sensitive words. Typically, the list is stored in a file. Here’s the code to read the content from the file:

$sensitive_file_path = 'sensitive_words.txt';
$sensitive_words = file($sensitive_file_path, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);

This code reads the sensitive words from the specified file path, storing each word in the array $sensitive_words while ignoring any empty lines and newline characters.

2.2 Building the Regular Expression

After reading the sensitive word list, the next step is to convert these words into a regular expression format for easy matching. Here’s the code for converting sensitive words into a regular expression:

$pattern = '/(' . implode('|', $sensitive_words) . ')/i';

This code joins the sensitive words with the '|' symbol and wraps them in the regular expression format '/…/i', which ensures case-insensitive matching.

2.3 Performing the Match

Once the regular expression is built, the next step is to use the preg_match() function to check the text that needs filtering. Here’s the code to perform the matching:

$filtered_text = preg_replace($pattern, '***', $text);

This code replaces any matched sensitive word in the $text with '***' and stores the filtered result in the $filtered_text variable.

2.4 Complete Code Example

Here’s a complete code example for implementing sensitive word filtering:

$sensitive_file_path = 'sensitive_words.txt';
$sensitive_words = file($sensitive_file_path, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
$pattern = '/(' . implode('|', $sensitive_words) . ')/i';
$filtered_text = preg_replace($pattern, '***', $text);

3. Conclusion

Through this article, we have learned how to implement sensitive word filtering in PHP, from reading the sensitive word list to building regular expressions and using preg_replace() to perform text matching and replacement, completing a full sensitive word filtering system.

When using a sensitive word filtering feature, it's important to regularly update the sensitive word list to ensure the filtering remains effective and accurate, preventing new sensitive words from being missed.