How to Safely Echo Default Values in HTML Forms Using PHP?

Safeguarding HTML Form Input Default Values in PHP

When echoing default values for HTML form fields using PHP, proper encoding is essential to prevent malicious input and safeguard your website. In the given snippets:

<input type="text" name="firstname" value="<?php echo $_POST['firstname']; ?>" />

and

<textarea name="content"><?php echo $_POST['content']; ?></textarea>

Ensure that the echoed $_POST variables are html-encoded to prevent cross-site scripting attacks and other vulnerabilities.

Solution:

To effectively escape these values in PHP, use the htmlspecialchars() function:

<?php echo htmlspecialchars($_POST['firstname']); ?>

and

<?php echo htmlspecialchars($_POST['content']); ?>

Always Escape Strings

As a rule of thumb, always html-encode strings before displaying them to users to prevent security risks. This applies not only to form input default values but to all strings that could potentially be user-generated or come from untrusted sources.

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