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    <p><strong>Question 1</strong></p> <blockquote> <p>Why is ~0xF equal to 0xFFFFFFF0?</p> </blockquote> <p>First, this means you run this on a 32-bit machine. That means 0xF is actually <code>0x0000000F</code> in <a href="http://en.wikipedia.org/wiki/Hexadecimal" rel="noreferrer">hexadecimal</a>, </p> <p>And that means 0xF is <code>0000 0000 0000 0000 0000 0000 0000 1111</code> in binary representation.</p> <p>The <code>~</code> operator means the NOT operation. Tt changes <em>every 0 to 1 and every 1 to 0</em> in the binary representation. That would make ~0xF to be: <code>1111 1111 1111 1111 1111 1111 1111 0000</code> in binary representation.</p> <p>And that is actually <code>0xFFFFFFF0</code>.</p> <p>Note that if you do this on a 16-bit machine, the answer of <code>~0xF</code> would be <code>0xFFF0</code>.</p> <p><strong>Question 2</strong></p> <p>You wrote the wrong statement, it should be <code>0xF &amp; 0x1</code>. Note that <code>0x1</code> <code>0x01</code>, <code>0x001</code>, and <code>0x0001</code> are all the same. So let’s change this hexdecimal number to binary representation:</p> <p><code>0xF</code> would be:</p> <p><code>0000 0000 0000 0000 0000 0000 0000 1111</code></p> <p>and <code>0x1</code> would be:</p> <p><code>0000 0000 0000 0000 0000 0000 0000 0001</code></p> <p>The <code>&amp;</code> operation follows the following rules:</p> <pre><code>0 &amp; 0 = 0 0 &amp; 1 = 0 1 &amp; 0 = 0 1 &amp; 1 = 1 </code></pre> <p>So doing that to every bit, you get the result:</p> <p><code>0000 0000 0000 0000 0000 0000 0000 0001</code></p> <p>which is actually <code>0x1</code>.</p> <p><strong>Additional</strong></p> <p><code>|</code> means bitwise OR operation. It follows:</p> <pre><code>0 | 0 = 0 0 | 1 = 1 1 | 0 = 1 1 | 1 = 1 </code></pre> <p><code>^</code> means bitwise XOR operation. It follows:</p> <pre><code>0 ^ 0 = 0 0 ^ 1 = 1 1 ^ 0 = 1 1 ^ 1 = 0 </code></pre> <p>You can get more information <a href="http://en.wikipedia.org/wiki/Bitwise_operation#XOR" rel="noreferrer">here</a>.</p>
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    1. POWhy is ~0xF equal to 0xFFFFFFF0 on a 32-bit machine?
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    1. USPeter Mortensen
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    1. COJust for the record, the list of rules given for AND, OR, and XOR are called truth tables, if it makes them easier to find.
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    2. CO@chris Thanks:)
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    3. COThanks, well explained!
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