let i have got two byte variable:
byte a= 255;
byte b= 121;
byte c= (byte) (a + b);
Console.WriteLine(c.ToString());
output:120
please explain me how this is adding values. i know that its crossing size limit of byte but don't know what exactly operation it performs in such situation because its not looking like its chopping the result.
Thanks
EDIT: sorry its 120 as a answer.
You are overflowing the byte storage of 255 so it starts from 0.
So: a + b is an integer = 376
Your code is equivalent to:
byte c = (byte)376;
That's one of the reasons why adding two bytes returns an integer. Casting it back to a byte should be done at your own risk.
If you want to store the integer 376 into bytes you need an array:
byte[] buffer = BitConverter.GetBytes(376);
As you can see the resulting array contains 4 bytes now which is what is necessary to store a 32 bit integer.
It gets obvious when you look at the binary representation of the values:
var | decimal | binary
----|----------------------
a | 255 | 1111 1111
b | 121 | 0111 1001
| |
a+b | 376 | 1 0111 1000
This gets truncated to 8 bits, the overflow bit is disregarded when casting the result to byte:
c | | 0111 1000 => 120
As others are saying, you are overflowing; the a+b operation results in an int, which you are explicitly casting to a byte. Documentation is here, essentially in an unchecked context, the cast is done by truncating the most significant bits.
I guess you mean byte c= (byte)(a + b);
On my end the result here is 120, and that is what I would expect.
a+b equals 376, and all bits that represent 256 and up gets stripped (since byte actually only hold 1 byte), then 120 is what you are left with inside your byte.
