how to get useragnet php code example

Example: php get browser

function get_browser_name($user_agent){
    $t = strtolower($user_agent);
    $t = " " . $t;
    if     (strpos($t, 'opera'     ) || strpos($t, 'opr/')     ) return 'Opera'            ;   
    elseif (strpos($t, 'edge'      )                           ) return 'Edge'             ;   
    elseif (strpos($t, 'chrome'    )                           ) return 'Chrome'           ;   
    elseif (strpos($t, 'safari'    )                           ) return 'Safari'           ;   
    elseif (strpos($t, 'firefox'   )                           ) return 'Firefox'          ;   
    elseif (strpos($t, 'msie'      ) || strpos($t, 'trident/7')) return 'Internet Explorer';
    return 'Unkown';
}
echo get_browser_name($_SERVER['HTTP_USER_AGENT']);//Chrome