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    <p>It does not make any difference to the value of <code>col</code> within the loop - assuming <code>col</code> is a primitive value. If <code>col</code> was a class, the prefix and postfix '++' operators might be overloaded to do two different things, although I would consider it bad practice. Consider the following example:</p> <pre><code>#include &lt;iostream&gt; using namespace std; int main() { for(int i = 0; i &lt; 10; i++) { cout &lt;&lt; i &lt;&lt; endl; } cout &lt;&lt; endl; for(int i = 0; i &lt; 10; ++i) { cout &lt;&lt; i &lt;&lt; endl; } } </code></pre> <p>Both of these just print out 0 to 9, despite the fact that you pre-increment in one, and post-increment in the other. The incrementation of <code>i</code> happens at the end of each run of the loop whether or not you use pre or post increment. I believe pre-incrementing is more efficient, since - and I may be wrong here - the compiler does not then need to use a temporary variable<sup>1.</sup>, but this would only be noticeable if you are looping for a very long time (and of course <a href="http://en.wikipedia.org/wiki/Program_optimization#Quotes" rel="noreferrer">'More computing sins are committed in the name of efficiency than for any other single reason'</a>.)</p> <p>As for question 2:</p> <blockquote> <p>Question 2 : Would using >>= 1U instead of =/2 make any difference ?</p> </blockquote> <p>Unlikely. Bit shifting would be faster if the compiler did not optimise, but chances are that your compiler will optimise this into a bit shift.</p> <p>As a side note, I generally find doing <code>unsigned variableName</code> (that is, dropping the <code>int</code>) bad practice - although C++ will shove in an <code>int</code> anywhere one is missing, it is less readable to me.</p> <p><strong>1.</strong>: Stephen in the comments (a <em>different</em> Stephen ;) ) notes that - "Pre-increment is more efficient for standard library container iterators, but it's no different for primitive types, since copying an integer is cheaper than copying a larger iterator (in particular std::set and std::map iterators)."</p>
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    1. COThat was comprehensive .
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    2. COPre-increment is more efficient for standard library container iterators, but it's no different for primitive types, since copying an integer is cheaper than copying a larger iterator (in particular std::set and std::map iterators). p.s. I am not the 'Stephen' that produced this answer
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    3. CO@Stephen Thank you, other Stephen. I shall include your answer. And then credit 'Stephen', of course :p.
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