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    <p>The <code>&gt;&gt;</code> operator performs a <a href="http://en.wikipedia.org/wiki/Arithmetic_shift" rel="nofollow noreferrer">bit shift</a>.</p> <p>The expression <code>&gt;&gt; 1</code> is almost* the same as <code>/ 2</code> so the programmer was calculating the index <code>colorList.Count / 2</code> which is** the <a href="http://en.wikipedia.org/wiki/Median" rel="nofollow noreferrer">median</a>. To understand why this is the case you need to look at the binary representation of the numbers involved. For example if you have 25 elements in your list:</p> <pre><code>n : 0 0 0 1 1 0 0 1 = 25 \ \ \ \ \ \ \ n &gt;&gt; 1: 0 0 0 0 1 1 0 0 = 12 </code></pre> <p>In general using a bitwise operator when really you want to perform a division is a bad practice. It is probably a premature optimization made because the programmer thought it would be faster to perform a bitwise operation instead of a division. It would be much clearer to write a division and I wouldn't be surprised if the performance of the two approaches is comparable.</p> <p>*The expression <code>x &gt;&gt; 1</code> gives the same result as <code>x / 2</code> for all positive integers and all negative even integers. However it gives a different result for negative odd integers. For example <code>-101 &gt;&gt; 1 == -51</code> whereas <code>-101 / 2 == -50</code>.</p> <p>**Actually the median is only defined this way if the list has an odd number of elements. For an even number of elements this method will strictly speaking not give the median.</p>
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    1. POWhat does the ">>" operator in C# do?
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    1. USMark Byers
    1. USMark Byers
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    1. POWhat does the ">>" operator in C# do?
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    1. COthanks a lot for the explanation .. i'm familiar with the shifting method and it's meaning but i didn't get that it's the way used here .. i have another question though .. is this way of dividing on 2 has less time complexity than the normal "/" division?
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      1. USMajd
    2. CO@Majd: That depends on the platform where you run the code. Remember that C# is compiled into CIL, which in turn is translated (“jitted”) into native machine code that differs from platform to platform. It may well be possible that some jitters automatically translate `x/2` into a shift-right instruction.
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    3. COIn the first footnote, it's a little confusing that you compare `x >> 1` with `x /= 2`, and I think the `=` sign is a typo. Of course `x >> 1` is comparable to `x / 2`, and `x >>= 1` is comparable to `x /= 2`.
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      1. USJeppe Stig Nielsen
 

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