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| 22 | <title>Shift Operations (GNU C Language Manual)</title>
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| 31 | <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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| 32 | <link href="Arithmetic.html" rel="up" title="Arithmetic">
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| 33 | <link href="Bits-Shifted-In.html" rel="next" title="Bits Shifted In">
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| 57 | <body lang="en">
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| 58 | <span id="Shift-Operations"></span><div class="header">
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| 59 | <p>
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| 60 | Next: <a href="Bitwise-Operations.html" accesskey="n" rel="next">Bitwise Operations</a>, Previous: <a href="Numeric-Comparisons.html" accesskey="p" rel="prev">Numeric Comparisons</a>, Up: <a href="Arithmetic.html" accesskey="u" rel="up">Arithmetic</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Symbol-Index.html" title="Index" rel="index">Index</a>]</p>
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| 61 | </div>
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| 62 | <hr>
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| 63 | <span id="Shift-Operations-1"></span><h3 class="section">6.7 Shift Operations</h3>
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| 64 | <span id="index-shift-operators"></span>
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| 65 | <span id="index-operators_002c-shift"></span>
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| 66 | <span id="index-operators_002c-shift-1"></span>
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| 67 | <span id="index-shift-count"></span>
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| 68 |
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| 69 | <p><em>Shifting</em> an integer means moving the bit values to the left or
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| 70 | right within the bits of the data type. Shifting is defined only for
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| 71 | integers. Here’s the way to write it:
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| 72 | </p>
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| 73 | <div class="example">
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| 74 | <pre class="example">/* <span class="roman">Left shift.</span> */
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| 75 | 5 << 2 ⇒ 20
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| 76 |
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| 77 | /* <span class="roman">Right shift.</span> */
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| 78 | 5 >> 2 ⇒ 1
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| 79 | </pre></div>
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| 80 |
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| 81 | <p>The left operand is the value to be shifted, and the right operand
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| 82 | says how many bits to shift it (the <em>shift count</em>). The left
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| 83 | operand is promoted (see <a href="Operand-Promotions.html">Operand Promotions</a>), so shifting never
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| 84 | operates on a narrow integer type; it’s always either <code>int</code> or
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| 85 | wider. The value of the shift operator has the same type as the
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| 86 | promoted left operand.
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| 87 | </p>
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| 88 | <table class="menu" border="0" cellspacing="0">
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| 89 | <tr><td align="left" valign="top">• <a href="Bits-Shifted-In.html" accesskey="1">Bits Shifted In</a></td><td> </td><td align="left" valign="top">How shifting makes new bits to shift in.
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| 90 | </td></tr>
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| 91 | <tr><td align="left" valign="top">• <a href="Shift-Caveats.html" accesskey="2">Shift Caveats</a></td><td> </td><td align="left" valign="top">Caveats of shift operations.
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| 92 | </td></tr>
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| 93 | <tr><td align="left" valign="top">• <a href="Shift-Hacks.html" accesskey="3">Shift Hacks</a></td><td> </td><td align="left" valign="top">Clever tricks with shift operations.
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| 94 | </td></tr>
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| 95 | </table>
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| 96 |
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| 97 |
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| 99 |
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