title tag function

function title_tag () {

    // 0. uppercase string
    $str = strtoupper ( $_SERVER['REQUEST_URI'] );

    // 1. remove trailing and init slash
    $str = trim ( $str , "https://wordpress.stackexchange.com/" );

    // 2. add search and replace chars; 
    // two array, with same element size, 
    // 1. element of search array will be replaced
    // with the first element of replace array
    $search = array (
        '-',
        "https://wordpress.stackexchange.com/"
    );

    $replace = array (
        ' ',
        ' - '
    );

    // 3. replace the chars
    $str = str_replace( $search , $replace , $str );

    // 4. replace the last occurance of - for ,
    // $pos finds the position of the last occurance
    // and fortunately, PHP strings can be manipulated 
    // as arrays, so replace the array element with the
    // character
    $pos = strrpos ( $str , '-' );
    $str{$pos} = ',';

    // you're ready
    return $str;
}