When to use Shift operators << >> in C#?

user_66708 0
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I was studying shift operators in C#, trying to find out when to use them in my code.

I found an answer but for Java, you could:

a) Make faster integer multiplication and division operations:

*4839534 * 4* can be done like this: 4839534 << 2

or

543894 / 2 can be done like this: 543894 >> 1

Shift operations much more faster than multiplication for most of processors.

b) Reassembling byte streams to int values

c) For accelerating operations with graphics since Red, Green and Blue colors coded by separate bytes.

d) Packing small numbers into one single long...

For b, c and d I can't imagine here a real sample.

Does anyone know if we can accomplish all these items in C#? Is there more practical use for shift operators in C#?

bit-shift operators c#
4 Answers

There is no need to use them for optimisation purposes because the compiler will take care of this for you.

Only use them when shifting bits is the real intent of your code (as in the remaining examples in your question). The rest of the time just use multiply and divide so readers of your code can understand it at a glance.

user_651070

Unless there is a very compelling reason, my opinion is that using clever tricks like that typically just make for more confusing code with little added value. The compiler writers are a smart bunch of developers and know a lot more of those tricks than the average programmer does. For example, dividing an integer by a power of 2 is faster with the shift operator than a division, but it probably isn't necessary since the compiler will do that for you. You can see this by looking at the assembly that both the Microsoft C/C++ compiler and gcc perform these optimizations.

user_234780

Check out these Wikipedia articles about the binary number system and the arithmetic shift. I think they will answer your questions.

The shift operators are rarely encountered in business applications today. They will appear frequently in low-level code that interacts with hardware or manipulates packed data. They were more common back in the days of 64k memory segments.

cdonner_588800
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