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| 22 | <title>Signed and Unsigned Types (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="Narrow-Integers.html" rel="next" title="Narrow Integers">
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| 57 | <body lang="en">
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| 58 | <span id="Signed-and-Unsigned-Types"></span><div class="header">
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| 59 | <p>
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| 60 | Next: <a href="Narrow-Integers.html" accesskey="n" rel="next">Narrow Integers</a>, Previous: <a href="Basic-Integers.html" accesskey="p" rel="prev">Basic Integers</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="Signed-and-Unsigned-Types-1"></span><h4 class="subsection">11.1.2 Signed and Unsigned Types</h4>
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| 64 | <span id="index-signed-types"></span>
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| 65 | <span id="index-unsigned-types"></span>
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| 66 | <span id="index-types_002c-signed"></span>
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| 67 | <span id="index-types_002c-unsigned"></span>
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| 68 | <span id="index-signed"></span>
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| 69 | <span id="index-unsigned"></span>
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| 70 |
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| 71 | <p>An unsigned integer type can represent only positive numbers and zero.
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| 72 | A signed type can represent both positive and negative number, in a
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| 73 | range spread almost equally on both sides of zero. For instance,
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| 74 | <code>unsigned char</code> holds numbers from 0 to 255 (on most computers),
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| 75 | while <code>signed char</code> holds numbers from -128 to 127. Each of
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| 76 | these types holds 256 different possible values, since they are both 8
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| 77 | bits wide.
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| 78 | </p>
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| 79 | <p>Write <code>signed</code> or <code>unsigned</code> before the type keyword to
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| 80 | specify a signed or an unsigned type. However, the integer types
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| 81 | other than <code>char</code> are signed by default; with them, <code>signed</code>
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| 82 | is a no-op.
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| 83 | </p>
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| 84 | <p>Plain <code>char</code> may be signed or unsigned; this depends on the
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| 85 | compiler, the machine in use, and its operating system.
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| 86 | </p>
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| 87 | <p>In many programs, it makes no difference whether <code>char</code> is
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| 88 | signed. When it does matter, don’t leave it to chance; write
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| 89 | <code>signed char</code> or <code>unsigned char</code>.<a id="DOCF3" href="#FOOT3"><sup>3</sup></a>
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| 90 | </p>
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| 91 | <div class="footnote">
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| 92 | <hr>
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| 93 | <h4 class="footnotes-heading">Footnotes</h4>
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| 94 |
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| 95 | <h5><a id="FOOT3" href="#DOCF3">(3)</a></h3>
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| 96 | <p>Personal note from
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| 97 | Richard Stallman: Eating with hackers at a fish restaurant, I ordered
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| 98 | Arctic Char. When my meal arrived, I noted that the chef had not
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| 99 | signed it. So I complained, “This char is unsigned—I wanted a
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| 100 | signed char!” Or rather, I would have said this if I had thought of
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| 101 | it fast enough.</p>
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| 102 | </div>
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| 103 |
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| 104 |
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| 105 |
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