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    <p>If I understand the question correctly, I actually think something like this is possible using a function overload. <a href="http://www.altdevblogaday.com/2011/10/27/quasi-compile-time-string-hashing/" rel="nofollow">Here's an article</a> that shows the basic idea. In your case I think it would be sufficient to have the following two overloads:</p> <pre><code>void f(char const *); template&lt;unsigned int N&gt; void f(char const (&amp;)[N]); </code></pre> <p>The latter should be invoked when the string is a string literal, the latter at other times. If the compiler is sufficiently good at optimizing then calls to the latter may be evaluated at compile time.</p> <p>EDIT:</p> <p>Alright, it bothered me that the above solution didn't work, so I did some playing around and I think I came up with a solution:</p> <pre><code>#include &lt;string&gt; #include &lt;boost/utility/enable_if.hpp&gt; template&lt;typename T&gt; struct is_string_literal { enum { value = false }; }; template&lt;unsigned int N&gt; struct is_string_literal&lt;char const (&amp;)[N]&gt; { enum { value = true }; }; template&lt;typename T&gt; typename boost::disable_if&lt;is_string_literal&lt;T&gt; &gt;::type foo(T) { std::cout &lt;&lt; "foo1" &lt;&lt; std::endl; } template&lt;int N&gt; void foo(char const (&amp;)[N]) { std::cout &lt;&lt; "foo2" &lt;&lt; std::endl; } int main( ) { std::string bar = "blah"; char const str[] = "blah"; foo(str); foo("blah"); foo(bar.data()); } </code></pre> <p>The output (on GCC 4.4 with -O3) is:</p> <pre><code>foo2 foo2 foo1 </code></pre> <p>I admit that I don't completely understand why this works when the previous solution didn't. Maybe there's something about overload resolution that I don't completely understand.</p>
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    1. POWays to distinguish string literal and runtime generated string
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    1. USChris Hayden
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    1. COThe non-template function is always a better match than template functions (try out the code and see which one is chosen).
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      1. USJesse Good
    2. COWell, this still relies on the optimization of the compiler and only works for simple `f_impl`. I don't think for functions as complicated as `printf` this technique helps.
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      1. USKan Li
    3. CO@Jesse Seems you're right. It does beg the question of how the author got the results he did in the post.
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