This article explains how to send HTML emails with embedded images using PHP and the PHPMailer library. It covers how to install PHPMailer, configure SMTP, compose HTML email content, and embed local images, helping developers easily send visually rich email messages.

We must be careful to avoid XSS (cross-site scripting attack) vulnerabilities when executing database queries and outputting data to HTML pages using PHP and MySQLi. This type of vulnerability usually occurs when directly outputting the content in the database to a web page without any escape or filtering.

When a browser accesses a web page, the server first establishes communication with the browser through the HTTP protocol. This process involves sending HTTP header information and subsequent HTML content. HTTP header information not only contains basic information of the web page (such as content type, character set, etc.), but also determines how the browser handles the page display, cache, jump and other behaviors.

The stripos function is a very useful tool to find where a string first appears in another string. Unlike strpos, strpos is case-insensitive, which makes it very convenient when checking HTML content, especially if you need to detect if a tag exists.

In modern web development, we often need to modify or replace attributes of a large number of HTML elements, especially in template systems or preprocessors. Using manual modification of properties is not only inefficient, but also prone to errors. This article will introduce how to implement HTML attributes through PHP scripts to improve development efficiency.

The preg_replace_callback_array function is a powerful tool that executes a callback function to replace it when a regular expression matches a specific pattern. It can handle complex string replacement operations, especially when you want to handle multiple patterns and callback functions, it provides a more concise and efficient way.

In PHP, BBCode is a lightweight markup language commonly used in forums and message boards, where it allows simple text formatting through a set of concise tags. Common BBCode syntax includes tags like [b] (bold), [i] (italic), and [url] (link). To convert BBCode to HTML, PHP's built-in regular expression function preg_replace_callback_array can be used to achieve this goal.

preg_replace_callback_array is a powerful regular expression function that helps us hand over the matching regular expression results to a callback function for processing, thereby dynamically replacing the string content. This function is very useful when dealing with text conversions like Markdown. Markdown is a lightweight markup language that is often used to format text content. Especially in the process of generating HTML pages, converting Markdown to HTML is a common requirement.