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PODifference between code generated using a template function and a normal function
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  1. PODifference between code generated using a template function and a normal function
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    copied!<p>I have a vector containing large number of elements. Now I want to write a small function which counts the number of even or odd elements in the vector. Since performance is a major concern I don't want to put an if statement inside the loop. So I wrote two small functions like:</p> <pre><code>long long countOdd(const std::vector&lt;int&gt;&amp; v) { long long count = 0; const int size = v.size(); for(int i = 0; i &lt; size; ++i) { if(v[i] &amp; 1) { ++count; } } return count; } long long countEven(const std::vector&lt;int&gt;&amp; v) { long long count = 0; const int size = v.size(); for(int i = 0; i &lt; size; ++i) { if(0 == (v[i] &amp; 1)) { ++count; } } return count; } </code></pre> <p>My question is can I get the same result by writing a single template function like this:</p> <pre><code>template &lt;bool countEven&gt; long long countTemplate(const std::vector&lt;int&gt;&amp; v1) { long long count = 0; const int size = v1.size(); for(int i = 0; i &lt; size; ++i) { if(countEven) { if(v1[i] &amp; 1) { ++count; } } else if(0 == (v1[i] &amp; 1)) { ++count; } } return count; } </code></pre> <p>And using it like this:</p> <pre><code>int main() { if(somecondition) { countTemplate&lt;true&gt;(vec); //Count even } else { countTemplate&lt;false&gt;(vec); //Count odd } } </code></pre> <p>Will the code generated for the template and non-template version be the same ? or will there be some additional instructions emitted?</p> <p>Note that the counting of numbers is just for illustration hence please don't suggest other methods for counting.</p> <p><strong>EDIT</strong>: Ok. I agree that it may not make much sense from performance point of view. But atleast from maintainability point of view I would like to have only one function to maintain instead of two. </p>
 

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