PHP实例——格式化文件尺寸

/**
 +----------------------------------------------------------
 * 字节格式化 把字节数格式为 B K M G T 描述的大小
 +----------------------------------------------------------
 * @return string
 +----------------------------------------------------------
*/
function byte_format($size, $dec=2)
{
$a = array("B", "KB", "MB", "GB", "TB", "PB");
$pos = 0;
while ($size >= 1024) {
$size /= 1024;
$pos++;
    }
return round($size,$dec)." ".$a[$pos];
}