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POVery poor boost::lexical_cast performance
 

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  1. POVery poor boost::lexical_cast performance
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    <p>Windows XP SP3. Core 2 Duo 2.0 GHz. I'm finding the boost::lexical_cast performance to be extremely slow. Wanted to find out ways to speed up the code. Using /O2 optimizations on visual c++ 2008 and comparing with java 1.6 and python 2.6.2 I see the following results.</p> <p><strong>Integer casting:</strong></p> <pre><code>c++: std::string s ; for(int i = 0; i &lt; 10000000; ++i) { s = boost::lexical_cast&lt;string&gt;(i); } java: String s = new String(); for(int i = 0; i &lt; 10000000; ++i) { s = new Integer(i).toString(); } python: for i in xrange(1,10000000): s = str(i) </code></pre> <p>The times I'm seeing are </p> <p>c++: 6700 milliseconds</p> <p>java: 1178 milliseconds</p> <p>python: 6702 milliseconds</p> <p>c++ is as slow as python and 6 times slower than java.</p> <p><strong>Double casting:</strong></p> <pre><code>c++: std::string s ; for(int i = 0; i &lt; 10000000; ++i) { s = boost::lexical_cast&lt;string&gt;(d); } java: String s = new String(); for(int i = 0; i &lt; 10000000; ++i) { double d = i*1.0; s = new Double(d).toString(); } python: for i in xrange(1,10000000): d = i*1.0 s = str(d) </code></pre> <p>The times I'm seeing are</p> <p>c++: 56129 milliseconds</p> <p>java: 2852 milliseconds</p> <p>python: 30780 milliseconds</p> <p>So for doubles c++ is actually half the speed of python and 20 times slower than the java solution!!. Any ideas on improving the boost::lexical_cast performance? Does this stem from the poor stringstream implementation or can we expect a general 10x decrease in performance from using the boost libraries. </p>
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    1. USJames McNellis
    1. USNaveen
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    1. CO-1 for immature editorializing and lack of perspective
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      1. POVery poor boost::lexical_cast performance
      1. USBarry Kelly
    2. COI removed the 'pathetic' comment, I agree that it was unnecessary. Interestingly, some work seems to have been done in fixing lexical_cast http://accu.org/index.php/journals/1375. So this means if you were to use this library in 2006 when people stopped maintaining it, you would see an additional 3-6x degradation in performance. While no doubt the library writers are exceptional C++ programmers, it would be helpful to step back and ask if providing a library of such genericity makes efficiency impossible. Consider the STL in contrast, where the efficiency and generality are preserved.
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      1. USNaveen
    3. CO@Barry Kelly: As a longtime C++ programmer I would have said "That's pathetic!" too if I'd seen those results! @Burkhard: I wish there was a way to downvote pointless hairsplitting comments like yours.
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