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| 22 | <title>Wide String Constants (GNU C Language Manual)</title>
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| 32 | <link href="Constants.html" rel="up" title="Constants">
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| 57 | <body lang="en">
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| 58 | <span id="Wide-String-Constants"></span><div class="header">
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| 59 | <p>
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| 60 | Previous: <a href="Wide-Character-Constants.html" accesskey="p" rel="prev">Wide Character Constants</a>, Up: <a href="Constants.html" accesskey="u" rel="up">Constants</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="Wide-String-Constants-1"></span><h3 class="section">12.11 Wide String Constants</h3>
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| 64 | <span id="index-wide-string-constants"></span>
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| 65 | <span id="index-constants_002c-wide-string"></span>
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| 66 |
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| 67 | <p>A <em>wide string constant</em> stands for an array of 16-bit or 32-bit
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| 68 | characters. They are rarely used; if you’re just
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| 69 | learning C, you may as well skip this section.
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| 70 | </p>
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| 71 | <p>There are three kinds of wide string constants, which differ in the
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| 72 | data type used for each character in the string. Each wide string
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| 73 | constant is equivalent to an array of integers, but the data type of
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| 74 | those integers depends on the kind of wide string. Using the constant
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| 75 | in an expression will convert the array to a pointer to its first
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| 76 | element, as usual for arrays in C (see <a href="Accessing-Array-Elements.html">Accessing Array Elements</a>).
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| 77 | For each kind of wide string constant, we state here what type that
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| 78 | pointer will be.
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| 79 | </p>
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| 80 | <dl compact="compact">
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| 81 | <dt><code>char16_t</code></dt>
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| 82 | <dd><p>This is a 16-bit Unicode wide string constant: each element is a
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| 83 | 16-bit Unicode character code with type <code>char16_t</code>, so the string
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| 84 | has the pointer type <code>char16_t *</code>. (That is a type designator;
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| 85 | see <a href="Pointer-Type-Designators.html">Pointer Type Designators</a>.) The constant is written as
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| 86 | ‘<samp>u</samp>’ (which must be lower case) followed (with no intervening
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| 87 | space) by a string constant with the usual syntax.
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| 88 | </p>
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| 89 | </dd>
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| 90 | <dt><code>char32_t</code></dt>
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| 91 | <dd><p>This is a 32-bit Unicode wide string constant: each element is a
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| 92 | 32-bit Unicode character code, and the string has type <code>char32_t *</code>.
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| 93 | It’s written as ‘<samp>U</samp>’ (which must be upper case) followed (with no
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| 94 | intervening space) by a string constant with the usual syntax.
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| 95 | </p>
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| 96 | </dd>
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| 97 | <dt><code>wchar_t</code></dt>
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| 98 | <dd><p>This is the original kind of wide string constant. It’s written as
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| 99 | ‘<samp>L</samp>’ (which must be upper case) followed (with no intervening
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| 100 | space) by a string constant with the usual syntax, and the string has
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| 101 | type <code>wchar_t *</code>.
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| 102 | </p>
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| 103 | <p>The width of the data type <code>wchar_t</code> depends on the target
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| 104 | platform, which makes this kind of wide string somewhat less useful
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| 105 | than the newer kinds.
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| 106 | </p></dd>
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| 107 | </dl>
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| 108 |
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| 109 | <p><code>char16_t</code> and <code>char32_t</code> are declared in the header file
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| 110 | <samp>uchar.h</samp>. <code>wchar_t</code> is declared in <samp>stddef.h</samp>.
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| 111 | </p>
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| 112 | <p>Consecutive wide string constants of the same kind concatenate, just
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| 113 | like ordinary string constants. A wide string constant concatenated
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| 114 | with an ordinary string constant results in a wide string constant.
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| 115 | You can’t concatenate two wide string constants of different kinds.
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| 116 | You also can’t concatenate a wide string constant (of any kind) with a
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| 117 | UTF-8 string constant.
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| 118 | </p>
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| 119 | <hr>
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| 120 | <div class="header">
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| 121 | <p>
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| 122 | Previous: <a href="Wide-Character-Constants.html" accesskey="p" rel="prev">Wide Character Constants</a>, Up: <a href="Constants.html" accesskey="u" rel="up">Constants</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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