What steps should be taken to activate the php_mbstring.dll extension library in PHP to avoid errors like "Call to undefined function: mb_internal_encoding()"?

To activate the php_mbstring.dll extension library in PHP and avoid errors like "Call to undefined function: mb_internal_encoding()", you need to enable the mbstring extension in your PHP configuration file (php.ini). Find the line `;extension=mbstring` in php.ini and remove the semicolon at the beginning to uncomment it. Save the file and restart your web server for the changes to take effect.

// Enable mbstring extension in php.ini
// Find the line ;extension=mbstring and remove the semicolon to uncomment it
// Save the file and restart the web server

// Example code using mb_internal_encoding after enabling the mbstring extension
if (extension_loaded('mbstring')) {
    mb_internal_encoding('UTF-8');
    echo mb_internal_encoding(); // Output: UTF-8
} else {
    echo "mbstring extension is not enabled!";
}