PHP file_get_contents after php has evaluated

I know how to use file_get_contents and fopen etc, but when I do it to one of my own file, I get the literal string, meaning, the code is not preprocessed! How can i import text from a file without using require etc. because I want to store the value开发者_开发百科 into a string

See examples #5 and #6 on the manual. Taken straight from there:

$string = get_include_contents('somefile.php');

function get_include_contents($filename) {
    if (is_file($filename)) {
        ob_start();
        include $filename;
        $contents = ob_get_contents();
        ob_end_clean();
        return $contents;
    }
    return false;
}