<< and >> operators in c#

  • Thread starter Thread starter Guest
  • Start date Start date
G

Guest

Hi,

I'm trying to figure out the purpose of these operators.
Now, I know what they do. They shift bits either left or right.
But I don't know why would anybody want to do that. I've never seen
anyone using it in his/her code.
Any ideas?

Thanks,
Ben
 
Ben said:
I'm trying to figure out the purpose of these operators.
Now, I know what they do. They shift bits either left or right.
But I don't know why would anybody want to do that. I've never seen
anyone using it in his/her code.
Click to expand...

I think you have seen too little code.

They are used - both for real bit manipulation
stuff and for multiplication and division with
powers of two.

Most CPU's actually implement them in their
native instruction set.


Arne
 
They are used - both for real bit manipulation
stuff and for multiplication and division with
powers of two.

Most CPU's actually implement them in their
native instruction set.
Click to expand...

In fact that's why we have them.

k = j << 3;

is a lot faster than

k = j * 8;
 
Ben said:
Hi,

I'm trying to figure out the purpose of these operators.
Now, I know what they do. They shift bits either left or right.
But I don't know why would anybody want to do that. I've never seen
anyone using it in his/her code.
Any ideas?
Click to expand...

it is a tragic mistake that an operator that is tailor made for piping
and adding to lists, is reserved instead for such a trivial, seldom
used operation. If you want to shift bits, better to have a new literal
operator:
bunchOfBits shiftleft 2 ;

-Steve
 
Maybe you would like to expand on the 'piping and 'adding' bits.

Also, what makes you think that bit-shifting is seldom used?
 
Stephany said:
Maybe you would like to expand on the 'piping and 'adding' bits.
Click to expand...

arrayOfLines << new string( "another line" ) ; // adds to the end
of the array
databaseTable << row ; // adds a row to the database table

the general rule being:
<< adds to something
= replaces the contents of something with something else.
Also, what makes you think that bit-shifting is seldom used?
Click to expand...

I have not used bit shifting for years. If you are looking to multiply
or divide, better to use those operators. ( and the optimized compilers
of today likely bit shift when we multiply by a constant that is a
power of 2. )

-Steve
 
arrayOfLines << new string( "another line" ) ; // adds to the end
of the array
databaseTable << row ; // adds a row to the database table

the general rule being:
<< adds to something
= replaces the contents of something with something else.
Click to expand...

And what language might that be defined in?
I have not used bit shifting for years. If you are looking to multiply
Click to expand...

Just because you personally have not used a powerful element of the language
for years, don't assume that other people don't use it regularly.
 
Stephany said:
And what language might that be defined in?
Click to expand...

a great language. one that also allows the programmer to define the
types that a class can be implicitly converted to. that is a feature
C# could benefit from. I dont like casting.
Just because you personally have not used a powerful element of the language
for years, don't assume that other people don't use it regularly.
Click to expand...

what do they use it for? I think it makes a poor bit shift because it
ties you too close to the byte size of what is being operated on and
the unit of measure is implied as bits. why not a syntax that allows
you to shift by bits, bytes, characters?
wordValue = wordValue ShiftLeft 2 Bytes ;

-Steve
 
Hi Steve,

that would be using an operator to change one of it's operands. I think this
is not an OOP way to do it. It surely is not a C#-like way to do. (Though it
would be possible.)
One should use an Add-method instead of that (like in StringBuilder) or the
+ operator like in string, if the type has value semantic.

I suppose the inventors of C# felt this use of the << and >> operators an
abuse of them, so they intentionally forbade it.
 
Steve said:
a great language. one that also allows the programmer to define the
types that a class can be implicitly converted to. that is a feature
C# could benefit from. I dont like casting.
Click to expand...

So you find << to be more obvious than list.Add(...) and you don't like
telling readers of your code when a conversion is taking place. I'm
beginning to spot a pattern here...

By the way, you *can* do implicit conversions in C#. There are some
restrictions, and personally I don't like them because they tend to
reduce readability, but they're available.

Jon
 
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