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    <blockquote> <p>Which is the "preferred" method in terms of good coding practice? I can fully understand why you would prefer version 2 if kSuperDescriptiveVarName is used more than once.</p> </blockquote> <p>Sounds like you understand the main point... factoring values (and their comments) that are used in multiple places. Further, it can sometimes help to have a group of constants in one place - so their values can be inspected, verified, modified etc. without concern for where they're used in the code. Other times, there are many constants used in proximity and the comments needed to properly explain them would obfuscate the code in which they're used.</p> <p>Countering that, having a <code>const</code> variable means all the programmers studying the code will be wondering whether it's used anywhere else, keeping it in mind as they inspect the rest of the scope in which it's declared etc. - the less unnecessary things to remember the surer the understanding of important parts of the code will be.</p> <p>Like so many things in programming, it's "an art" balancing the pros and cons of each approach, and best guided by experience and knowledge of the way the code's likely to be studied, maintained, and evolved. </p> <blockquote> <p>Also, does the compiler do any optimizations to make both versions effectively the same executable code? That is, are there any performance implications here?</p> </blockquote> <p>There's no performance implications in optimised code.</p> <blockquote> <p>I fully understand that using sizeof versus a raw literal is preferred for portability and also readability concerns.</p> </blockquote> <p>And other reasons too. A big factor in good programming is reducing the points of maintenance when changes are done. If you can modify the type of a variable and know that all the places using that variable will adjust accordingly, that's great - saves time and potential errors. Using <code>sizeof</code> helps with that.</p> <blockquote> <p>Which is preferred [for calculating offsets in a struct]? Does is still make sense to show all the steps involved with computing the offset or does the literal usage make sense here?</p> </blockquote> <p>The <code>offsetof</code> macro (<code>#include &lt;cstddef&gt;</code>) is better for this... again reducing maintenance burden. With the <em>this + that</em> approach you illustrate, if the compiler decides to use any padding your offset will be wrong, and further you have to fix it every time you add or remove a field.</p> <p>Ignoring the offsetof issues and just considering your <em>this + that</em> example as an illustration of a more complex value to assign, again it's a balancing act. You'd definitely want some explanation/comment/documentation re intent here (are you working out the binary size of earlier fields? calculating the offset of the next field?, deliberately missing some fields that might not be needed for the intended use or was that accidental?...). Still, a named constant might be enough documentation, so it's likely unimportant which way you lean....</p>
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