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| 22 | <title>Narrow Integers (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="Integer-Types.html" rel="up" title="Integer Types">
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| 33 | <link href="Integer-Conversion.html" rel="next" title="Integer Conversion">
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| 58 | <span id="Narrow-Integers"></span><div class="header">
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| 59 | <p>
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| 60 | Next: <a href="Integer-Conversion.html" accesskey="n" rel="next">Integer Conversion</a>, Previous: <a href="Signed-and-Unsigned-Types.html" accesskey="p" rel="prev">Signed and Unsigned Types</a>, Up: <a href="Integer-Types.html" accesskey="u" rel="up">Integer Types</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="Narrow-Integers-1"></span><h4 class="subsection">11.1.3 Narrow Integers</h4>
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| 64 |
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| 65 | <p>The types that are narrower than <code>int</code> are rarely used for
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| 66 | ordinary variables—we declare them <code>int</code> instead. This is
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| 67 | because C converts those narrower types to <code>int</code> for any
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| 68 | arithmetic. There is literally no reason to declare a local variable
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| 69 | <code>char</code>, for instance.
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| 70 | </p>
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| 71 | <p>In particular, if the value is really a character, you should declare
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| 72 | the variable <code>int</code>. Not <code>char</code>! Using that narrow type can
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| 73 | force the compiler to truncate values for conversion, which is a
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| 74 | waste. Furthermore, some functions return either a character value,
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| 75 | or -1 for “no character.” Using <code>int</code> keeps those
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| 76 | values distinct.
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| 77 | </p>
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| 78 | <p>The narrow integer types are useful as parts of other objects, such as
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| 79 | arrays and structures. Compare these array declarations, whose sizes
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| 80 | on 32-bit processors are shown:
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| 81 | </p>
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| 82 | <div class="example">
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| 83 | <pre class="example">signed char ac[1000]; /* <span class="roman">1000 bytes</span> */
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| 84 | short as[1000]; /* <span class="roman">2000 bytes</span> */
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| 85 | int ai[1000]; /* <span class="roman">4000 bytes</span> */
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| 86 | long long all[1000]; /* <span class="roman">8000 bytes</span> */
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| 87 | </pre></div>
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| 88 |
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| 89 | <p>In addition, character strings must be made up of <code>char</code>s,
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| 90 | because that’s what all the standard library string functions expect.
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| 91 | Thus, array <code>ac</code> could be used as a character string, but the
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| 92 | others could not be.
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| 93 | </p>
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| 94 |
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| 95 |
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| 96 |
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| 98 | </html>
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