PHP友好显示文件大小适合阅读

/**
 * Returns a human readable filesize
 *
 * @author      wesman20 (php.com)
 * @author      Jonas John
 * @version     0.3
 */
function HumanReadableFilesize($size) {
 
    // Adapted from: http://www.php.com/manual/en/function.filesize.php
 
    $mod = 1024;
 
    $units = explode(' ','B KB MB GB TB PB');
    for ($i = 0; $size > $mod; $i++) {
        $size /= $mod;
    }
 
    return round($size, 2) . ' ' . $units[$i];
}