Convert string to lowercase AND then convert it to its original form in PHP, is it possible?

PHP Snippet 1:

echo $original_string = "ORIGINAL UPPER CASE STRING and Camel Case or mIXed cASe";
echo "<br>";
echo $lowercased_string = strtolower($original_string) . " this has been converted.";
echo "<br>";
echo "The below is now in uppercase.";
echo "<br>";
echo $modified_string = strtoupper($original_string);
echo "<br>";

$var = $original_string . " is the original value.";
echo $var;

PHP Snippet 2:

echo strtolower("THIS WILL ALL BE LOWERCASE.");

PHP Snippet 3:

echo strtoupper("this will all be upper case");