What is the function quoted_printable_decode() used for in PHP and when should it be applied?

The function quoted_printable_decode() in PHP is used to decode a quoted-printable string. Quoted-printable is a method of encoding non-ASCII characters in email messages. This function is useful when you need to decode quoted-printable encoded text, such as when working with email messages or data that has been encoded in this format.

// Example usage of quoted_printable_decode() function
$encoded_text = "Hello=20World=21";
$decoded_text = quoted_printable_decode($encoded_text);

echo $decoded_text; // Output: Hello World!