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84 lines
4.1 KiB
HTML
84 lines
4.1 KiB
HTML
4 years ago
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<title>Long Long - Using the GNU Compiler Collection (GCC)</title>
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<meta name="description" content="Using the GNU Compiler Collection (GCC)">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="C-Extensions.html#C-Extensions" title="C Extensions">
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<link rel="prev" href="_005f_005fint128.html#g_t_005f_005fint128" title="__int128">
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<link rel="next" href="Complex.html#Complex" title="Complex">
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Copyright (C) 1988-2015 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being ``Funding Free Software'', the Front-Cover
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(see below). A copy of the license is included in the section entitled
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``GNU Free Documentation License''.
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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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(b) The FSF's Back-Cover Text is:
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You have freedom to copy and modify this GNU Manual, like GNU
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<body>
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<div class="node">
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<a name="Long-Long"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="Complex.html#Complex">Complex</a>,
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Previous: <a rel="previous" accesskey="p" href="_005f_005fint128.html#g_t_005f_005fint128">__int128</a>,
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Up: <a rel="up" accesskey="u" href="C-Extensions.html#C-Extensions">C Extensions</a>
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<hr>
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</div>
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<h3 class="section">6.9 Double-Word Integers</h3>
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<p><a name="index-g_t_0040code_007blong-long_007d-data-types-2905"></a><a name="index-double_002dword-arithmetic-2906"></a><a name="index-multiprecision-arithmetic-2907"></a><a name="index-g_t_0040code_007bLL_007d-integer-suffix-2908"></a><a name="index-g_t_0040code_007bULL_007d-integer-suffix-2909"></a>
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ISO C99 supports data types for integers that are at least 64 bits wide,
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and as an extension GCC supports them in C90 mode and in C++.
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Simply write <code>long long int</code> for a signed integer, or
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<code>unsigned long long int</code> for an unsigned integer. To make an
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integer constant of type <code>long long int</code>, add the suffix ‘<samp><span class="samp">LL</span></samp>’
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to the integer. To make an integer constant of type <code>unsigned long
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long int</code>, add the suffix ‘<samp><span class="samp">ULL</span></samp>’ to the integer.
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<p>You can use these types in arithmetic like any other integer types.
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Addition, subtraction, and bitwise boolean operations on these types
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are open-coded on all types of machines. Multiplication is open-coded
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if the machine supports a fullword-to-doubleword widening multiply
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instruction. Division and shifts are open-coded only on machines that
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provide special support. The operations that are not open-coded use
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special library routines that come with GCC.
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<p>There may be pitfalls when you use <code>long long</code> types for function
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arguments without function prototypes. If a function
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expects type <code>int</code> for its argument, and you pass a value of type
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<code>long long int</code>, confusion results because the caller and the
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subroutine disagree about the number of bytes for the argument.
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Likewise, if the function expects <code>long long int</code> and you pass
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<code>int</code>. The best way to avoid such problems is to use prototypes.
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</body></html>
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