<input type="submit" name="action" value="?">

 <?php $to_do = $_POST[&#39;action&#39;];
    if ($to_do == "&#10008;") {
       echo "I will delete the data for you";
    } else {
       echo "Operation does not match";
    }
?>

To solve this problem elegantly, we should separate the user interface display (i.e., special symbols) from the backend logical values ??(i.e., the string used to determine the operation). The HTML element provides a perfect solution for this.

The element allows us to set a value attribute for it. The value of this value attribute will be sent to the server when the form is submitted. At the same time, the content inside the element (which can be text, HTML entities, or more complex HTML structures) is used to display to the user.

Sample code:

Instead of using input type="submit", we use :

 <!-- Buttons in HTML forms -->

In this example:

• What users see on the web page is a button with a "?" symbol.
• When the user clicks this button to submit the form, the value ("delete") corresponding to name="action" will be sent to the server.

PHP backend verification:

Instead of dealing with complex Unicode entities, PHP scripts can now simply compare a clear, easy-to-understand string:

 <?php // process.php file if (isset($_POST[&#39;action&#39;])) {
        $to_do = $_POST[&#39;action&#39;];

        if ($to_do == "delete") {
           echo "I will delete the data for you";
        } else {
           echo "Unknown operation: " .htmlspecialchars($to_do);
        }
    } else {
        echo "No operation instructions received.";
    }
?>

In this way, we successfully decouple the user interface display from the backend logic. The PHP backend always receives a clear, consistent string (e.g. "delete"), thus avoiding validation issues caused by Unicode entity decoding.

Advantages and Considerations

1. Clear logic separation: This approach clearly separates the user interface (display symbols) and back-end logic (actual operation instructions), making the code easier to understand and maintain.
2. Improved readability: PHP code compares semantic strings such as "delete" instead of illegible Unicode entities or characters, which improves the readability of the code.
3. Avoid decoding issues: Completely avoids the complexity of how browsers decode HTML entities and how PHP handles these decoded characters.
4. Flexibility: The element can contain rich HTML content inside it, not just text or entities, which provides greater flexibility in button design.

Further reference:

For detailed information about the HTML element, you can consult the MDN Web Docs: http://ipnx.cn/link/2b31595206d7115ea2bcdc2a0fcd6757

Summarize

When you need to use special symbols as user interaction elements in HTML forms and want to make accurate judgments based on these interactions in the PHP backend, it is recommended to use the HTML element. By setting the value attribute to the logical string required by the backend, while displaying user-friendly Unicode symbols in the button content, the problem of HTML entities causing PHP validation failure after form submission can be effectively solved, thereby building a more robust and easier to maintain web application.

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