https://svn.boost.org/trac10/ticket/5651 <p> to_[lower/upper]_copy implicitly deduces the return type from the input type unless you supply the output as a second parameter. This is not always possible, consider for example: const std::string example = to_lower_copy&lt; std::string &gt;("foo") + to_upper_copy&lt; std::string &gt;("bar"); . To achieve the same we currently need to construct an additional unnecessary temporary which only purpose is to inform the algorithm of the return type. The attached case_conv.hpp introduces 1 new overload for each variant which shouldn't break any existing code. Discussion can be found at: <a class="ext-link" href="http://lists.boost.org/Archives/boost/2011/06/183031.php"><span class="icon">​</span>http://lists.boost.org/Archives/boost/2011/06/183031.php</a> . </p> en-us /htdocs/site/boost.png https://svn.boost.org/trac10/ticket/5651 Trac 1.4.3 sairony@… Tue, 28 Jun 2011 11:40:57 GMT https://svn.boost.org/trac10/ticket/5651 https://svn.boost.org/trac10/ticket/5651 <ul> <li><strong>attachment</strong> → <span class="trac-field-new">case_conv.hpp</span> </li> </ul> <p> Modified for 2 new overloads </p> Ticket Marshall Clow Wed, 28 Dec 2011 18:56:50 GMT https://svn.boost.org/trac10/ticket/5651#comment:1 https://svn.boost.org/trac10/ticket/5651#comment:1 <ul> <li><strong>owner</strong> changed from <span class="trac-author">Pavol Droba</span> to <span class="trac-author">Marshall Clow</span> </li> <li><strong>component</strong> <span class="trac-field-old">string_algo</span> → <span class="trac-field-new">algorithm</span> </li> </ul> Ticket