C # use the "|" operation to combine multiple

A few days ago, I saw a piece of code int I = GetCount (para1 | para2). It seems a bit strange. How can I transmit a parameter with an OR operation? In fact, there is something special here, I checked the materials from various parties and found out what I had to do in the QQ group. This operation can be used for multiple combinations. For example, when designing A permission, you will certainly design it like this: Permission A, what to do, permission B, what to do, permission C, and what to do... this Defines permissions. When calling A processing function, we can directly upload the corresponding permission Id. If user A has the permission, I must explicitly upload the Id of permission, user B has B permission. It seems reasonable to pass the Id of B permission. However, what if user C has both the and B permissions? You may say that I have set the AB permission when defining the permissions, in this way, all users with permissions A and B can pass the Id of AB '. I thought so at the beginning. However, this practice is not recommended, it is also not clever. If a user also has the ABC permission, BC permission, or CD permission, then I don't need to do anything, so I have been defining the type for it. We recommend that you use the "|" operation to combine parameters and split them with the "&" operation. In this way, callers can combine them at will. For processors, then, only the basic single processing "&" judgment can be defined. Example: Define an enumeration to indicate the permission type: copy the code public enum Privilege {Read = 0x01, Write = 0x02, Add = 0x04, delete = 0x08,} copy the Code to define a handler: copy the code public void GetPrivilege (Privilege pri) {if (pri & Privilege. read) = Privilege. read) {// do something} if (pri & Privilege. write) = Privilege. write) {// do something} if (pri & Privilege. add) = Privilege. add) {// do something} if (pri & Privilege. delete) = Privilege. del Ete) {// do something} copy the code and call it elsewhere: copy the code... getPrivilege (Privilege. read); GetPrivilege (Privilege. write); GetPrivilege (Privilege. add); GetPrivilege (Privilege. delete); GetPrivilege (Privilege. read | Privilege. write); GetPrivilege (Privilege. write | Privilege. add); GetPrivilege (Privilege. read | Privilege. write | Privilege. add );... copy the code and you will see that each call is executed accurately. Why is this possible? Based on the defined enumeration, the corresponding values are 0x010x020x040x08. Why can't I define 0x01,0x02,0x03,0x04, this is dependent on the "|" and "&" operations I mentioned at the beginning. The "|" or operation is 1 if the value of one is 1, "&" and the operation are both 1 to 1. Convert 0x01,0x02,0x04 and 0x08 to a binary system of 0001001001001000.