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POUnderstanding the Justification for different Pointer Types
 

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    <p>As a consious decision to create seperate model for pointer and non pointer data types Microsoft came up with a set of Data Types, which was stronly suggested to use them rather than POD like <code>int</code>, <code>__int64</code>, <code>long</code> (both <code>signed</code> and <code>unsigned</code> version).</p> <p>The Current Model Microsoft Follows is <code>IL32P64</code> which forced all the C Type cast of pointers to Integer Types vulnurable to pointer truncation. This forced them to come up with _PTR Types. For Each of the valid Integer Types (signed unsiged) like <code>long</code>, <code>int</code> or non POD Types like <code>DWORD</code>, they came up with the equivalent notation <code>DWORD_PTR</code>, <code>INT_PTR</code>.</p> <p>If we resolve the chain of typedefs, all these types boils down to the following defination</p> <pre><code>#if defined(_WIN64) typedef unsigned __int64 ULONG_PTR; #else typedef unsigned long ULONG_PTR; #endif #if defined(_WIN64) typedef unsigned __int64 LONG_PTR; #else typedef unsigned long LONG_PTR; #endif </code></pre> <p>What I would like to know, the reason to create different type defs for each Integer Types and non-POD equivalent rather than creating a single type to be used by all (say just one <code>INT_PTR</code> and <code>UINT_PTR</code>)</p> <p><strong>So Why do I want to know?</strong></p> <p>If you are always in MS Platform, its seldom a problem as to what MS Comes up with. Problem happens if your code is poly-platform. You have to define the equivalent types for *nix to make your code portable. </p> <p>I was planning to create only two Pointer Types say <code>XI64_PTR</code> and <code>XU64_PTR</code> with an equivalent defination and use it irrespective of what the previous types were.</p>
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    1. COPossible duplicate: http://stackoverflow.com/questions/1271748/dword-ptr-int-ptr-long-ptr-uint-ptr-ulong-ptr-when-how-and-why
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    2. CO@CongXu: If you compare both the questions, they address two different problems.
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    3. CO"You have to define the equivalent types for *nix" — that's not true. You don't have to. Use types described in C++ standard, and you will be fine, with safe and sound, portable C++ code.
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