asp.net C # bitwise AND, bitwise, or combination

ASP tutorials. NET C # bitwise AND, bitwise, or combination
First, each number of permissions is 2 of the N-second square number

such as: k1=2; Add to

k2=4; Delete

k3=8; Modify

...

This defines the number of functional permissions, and when you need to combine permissions, you need to bitwise or for each number of permissions you have.

Such as:

purview = K2|K3; assigning to add and remove permissions

When you need to determine whether you have a certain permission in the permission string, you need to place a bitwise AND.

Such as:

if ((Purview & K1) >0)//Determines whether this permission string has add permissions, the result >0 into the If statement code block

{

....

}

There's got to be some doubt about this, so don't worry, I'll explain it carefully.

First, the 8-bit binary value of 2 is 00000010

The 8-bit binary value of 4 is 00000100

The 8-bit binary value of 8 is 00001000

Second, when the 8 and 4 are bitwise OR manipulated, the result is:

4|8 = 12

00000100 |00001000 = 00001100

Why is that so? 00000001|00000001=00000001 00000001|00000000=1; 00000000|00000000=00000000 in the case of a bitwise OR operation;

In other words, except the 0|0 result is 0, the other results are 1

So 00000100 |00001000 = 00001100

Also say above purview = K2|K3 Binary Value result is purview = 00000100 |00001000 = 00001100.

Third, when the 8 and 4 are bitwise and manipulated, the result is:

4&8=0

00000100 &00001000 = 00000000

And why is that so? 00000001&00000001=00000001 00000001&00000000=00000000; 00000000&00000000=00000000 at the time of bitwise AND operation;

In other words, except the 1&1 result is 1, the other results are 0

So 00000100 &00001000 = 00000000

The result of the if ((Purview & K1) >0) above is 00001100&00000010 =00000000 (0>0) =false

The result of the same if ((Purview & K2) >0) is 00001100&00000100 =00000100=4=k2 (4>0) =true

In this way we understand the combination of permission strings and the principle of judging permissions, the white is to 2n the number of bitwise AND and bitwise OR