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    <p>Just like the <code>&amp;</code> and <code>&amp;&amp;</code> operator, the double Operator is a "short-circuit" operator.</p> <p>For example:</p> <pre><code>if(condition1 || condition2 || condition3) </code></pre> <p>If condition1 is true, condition 2 and 3 will NOT be checked.</p> <pre><code>if(condition1 | condition2 | condition3) </code></pre> <p>This will check conditions 2 and 3, even if 1 is already true. As your conditions can be quite expensive functions, you can get a good performance boost by using them.</p> <p>There is one big caveat, NullReferences or similar problems. For example:</p> <pre><code>if(class != null &amp;&amp; class.someVar &lt; 20) </code></pre> <p>If class is null, the if-statement will stop after <code>class != null</code> is false. If you only use &amp;, it will try to check <code>class.someVar</code> and you get a nice <code>NullReferenceException</code>. With the Or-Operator that may not be that much of a trap as it's unlikely that you trigger something bad, but it's something to keep in mind.</p> <p>No one ever uses the single <code>&amp;</code> or <code>|</code> operators though, unless you have a design where each condition is a function that HAS to be executed. Sounds like a design smell, but sometimes (rarely) it's a clean way to do stuff. The <code>&amp;</code> operator does "run these 3 functions, and if one of them returns false, execute the else block", while the <code>|</code> does "only run the else block if none return false" - can be useful, but as said, often it's a design smell.</p> <p>There is a Second use of the <code>|</code> and <code>&amp;</code> operator though: <a href="http://www.c-sharpcorner.com/UploadFile/chandrahundigam/BitWiserOpsInCS11082005050940AM/BitWiserOpsInCS.aspx" rel="noreferrer">Bitwise Operations</a>.</p>
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    1. POWhat is the difference between the | and || or operators?
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    1. USMichael Stum
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    1. POWhat is the difference between the | and || or operators?
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    1. COYeah, I didn't believe it until I created a console app - but good lord! Why would they give you the rope to hang yourself! I hated that about VB.NET - the OrElse and AndAlso keywords!
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      1. USJarrod Dixon
    2. COLove the short-circuit nature of these commands! I use this all the time to only execute the second check if the first succeeds, a null-object check for example: if(myObj != null && myObj.resultCode == 0) Console.WriteLine("Yay!");
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      1. USjoshperry
    3. COOf course maybe I should read the whole answer before I duplicate part of it!
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