復制代碼 代碼如下:

news:3,gallery:1,users:15

復制代碼 代碼如下:

1 = 1 = 20
3 = 1 + 2 = 20 + 21
15 = 1 + 2 + 4 + 8 = 20 + 21 + 22 + 23

復制代碼 代碼如下:

1 = Convert.ToInt32(1)
3 = Convert.ToInt32(1|2)
15= Convert.ToInt32(1|2|4|8)

復制代碼 代碼如下:

/// <summary>
/// 1添加，2修改，4刪除,8管理列表
/// </summary>
public enum Perm
{
add = 1,
update = 2,
delete = 4,
readlist = 8
}

復制代碼 代碼如下:

7 = 1 + 2 + 4 = 20 + 21 + 22 = 2 3 - 1

復制代碼 代碼如下:

Sigma ( 2n , n 是自然數 ) = 2n+1 - 1 ，即 1 + 2 + 4 + 8 + .... + 64 = 128 - 1 = 127