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| <a name="Arrays-and-pointers"></a> |
| <h3 class="section">4.7 Arrays and pointers</h3> |
| |
| <ul> |
| <li> <cite>The result of converting a pointer to an integer or |
| vice versa (C90 6.3.4, C99 and C11 6.3.2.3).</cite> |
| |
| <p>A cast from pointer to integer discards most-significant bits if the |
| pointer representation is larger than the integer type, |
| sign-extends<a name="DOCF2" href="#FOOT2"><sup>2</sup></a> |
| if the pointer representation is smaller than the integer type, otherwise |
| the bits are unchanged. |
| </p> |
| <p>A cast from integer to pointer discards most-significant bits if the |
| pointer representation is smaller than the integer type, extends according |
| to the signedness of the integer type if the pointer representation |
| is larger than the integer type, otherwise the bits are unchanged. |
| </p> |
| <p>When casting from pointer to integer and back again, the resulting |
| pointer must reference the same object as the original pointer, otherwise |
| the behavior is undefined. That is, one may not use integer arithmetic to |
| avoid the undefined behavior of pointer arithmetic as proscribed in |
| C99 and C11 6.5.6/8. |
| </p> |
| </li><li> <cite>The size of the result of subtracting two pointers to elements |
| of the same array (C90 6.3.6, C99 and C11 6.5.6).</cite> |
| |
| <p>The value is as specified in the standard and the type is determined |
| by the ABI. |
| </p> |
| </li></ul> |
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| <hr> |
| <h4 class="footnotes-heading">Footnotes</h4> |
| |
| <h3><a name="FOOT2" href="#DOCF2">(2)</a></h3> |
| <p>Future versions of GCC may zero-extend, or use |
| a target-defined <code>ptr_extend</code> pattern. Do not rely on sign extension.</p> |
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