LongWord: what changed
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Title: LongWord Longword
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| 1 | | - | A **[`longWord`](https://www.freepascal.org/docs-html/rtl/system/longword.html)** is an unsigned integer data type which is *larger* than a [[Word|word]].<sup>[1](https://www.gnu-pascal.de/gpc/LongWord.html)</sup> Larger refers to both the permissible range of values and the [[SizeOf|size]] occupied in a [[Packed|packed]] structure. |
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| 3 | | - | ## Definition |
| 4 | | - | |
| 5 | | - | ### GNU Pascal Compiler |
| 6 | | - | |
| 7 | | - | In [[GNU Pascal]] a `longWord` is compatible to GNU [[Pascal for C users|C]]’s [`long long unsigned int`](https://www.freepascal.org/docs-html/rtl/ctypes/culonglong.html). On *some* platforms it is 64 bits wide and thus has a range of `0..18446744073709551615` ($`\mathbb{Z} \cap \left[0, 2^{64}\right)`$). |
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| 9 | | - | ### Free Pascal Compiler |
| 10 | | - | |
| 11 | | - | For compatibility with [[Delphi]], the [[FPC]] *always* defines `longWord` as a 32-bit quantity, thus it may assume a value in the range `0..4294967295` ($`\mathbb{Z} \cap \left[0, 2^{32}\right)`$). The defunct [[Mode GPC|{$mode GPC}]] [[Compiler Mode|compiler compatibility mode]] did not change this. In this definition, [`dWord`](https://www.freepascal.org/docs-html/rtl/system/dword.html) (double word) is an alias for `longWord`. As of version 3.2.0 the data type [[Cardinal|cardinal]] is an *unconditional* alias for `longWord`. |
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| 13 | | - | ## Application |
| 14 | | - | |
| 15 | | - | - Because the FPC’s definition is fixed in size, it is frequently used when defining the *exact* memory layout of [[Record|record]] data types that will be passed to foreign language libraries. If the external library is written C, use of the [`cTypes unit`](https://www.freepascal.org/docs-html/rtl/ctypes/index.html) is recommended. |
| 16 | | - | - Likewise, the GPC guarantees compatibility of certain integer data types with GNU C.<sup>[2](https://www.gnu-pascal.de/gpc/Summary-of-Integer-Types.html)</sup> For maximum range, the GPC also defines `longestWord`. |
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| 18 | | - | ## See Also |
| 19 | | - | |
| 20 | | - | - [[Longint|longInt]] |
| 21 | | - | - [`pLongWord`](https://www.freepascal.org/docs-html/rtl/system/plongword.html) |
| 22 | | - | - [`types.tLongWordDynArray`](https://www.freepascal.org/docs-html/rtl/types/tlongworddynarray.html) |
| 23 | | - | |
| 24 | | - | --- |
| 25 | | - | *From the Free Pascal wiki, page "LongWord", as it stood on 2023-12-22 after a change by Alextpp, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).* |
| 1 | + | #REDIRECT [[LongWord]] |
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