title: String (const char*, size_t) to int?
body: <p>What's the fastest way to convert a string represented by (const char*, size_t) to an int?</p>
  
  <p>The string is <em>not</em> null-terminated.
  Both these ways involve a string copy (and more) which I'd like to avoid.</p>
  
  <p>And yes, this function is called a few million times a second. :p</p>
  
  <pre><code>int to_int0(const char* c, size_t sz)
  {
      return atoi(std::string(c, sz).c_str());
  }
  
  int to_int1(const char* c, size_t sz)
  {
      return boost::lexical_cast&lt;int&gt;(std::string(c, sz));
  }
  </code></pre>