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Bitwise OR

var iResult = 25 & 3;

alert(iResult); //outputs “1”

The result of a bitwise AND between 25 and 3 is 1. Why is that? Take a look:

25 = 0000 0000 0000 0000 0000 0000 0001 1001

3 = 0000 0000 0000 0000 0000 0000 0000 0011

---------------------------------------------

AND = 0000 0000 0000 0000 0000 0000 0000 0001

As you can see, only one bit (bit 0) contains a 1 in both 25 and 3. Because of this, every other bit of the

resulting number is set to 0, making the result equal to 1.

Bitwise OR

The bitwise OR operator is indicated by the pipe (

) and also works directly on the binary form of num-

bers. Essentially, bitwise OR follows these rules when evaluating bits:

Bit from First Number Bit from Second Number

Result

Using the same example as for bitwise AND, if you want to OR the numbers 25 and 3 together, the code

looks like this:

var iResult = 25 | 3;

alert(iResult); //outputs “27”

The result of a bitwise OR between 25 and 3 is 27:

25 = 0000 0000 0000 0000 0000 0000 0001 1001

3 = 0000 0000 0000 0000 0000 0000 0000 0011

---------------------------------------------

OR = 0000 0000 0000 0000 0000 0000 0001 1011

As you can see, four bits contain 1 in either number, so these are passed through to the result. The binary

code 11011 is equal to 27.

Bitwise XOR

The bitwise XOR operator is indicated by a caret (

) and, of course, works directly on the binary form of

numbers. Bitwise XOR is different from bitwise OR in that it returns 1 only when exactly one bit has a

value of 1. Here is the truth table:

Chapter 2

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