title: toupper/tolower + locale (german)
body: <p>how to convert a string (wstring) from lowercase to uppercase characters and vice versa?
  I searched the net and found there is a STL-function std::transform.<br>
  But until now I hav'nt figured out how to give the right locale-object for example "Germany_german" to the function. 
  Who can help please?
  my code looks like:  </p>
  
  <pre><code>wstring strin = L"ABCÄÖÜabcäöü";
  wstring str = strin;
  locale loc( "Germany_german" ); // ??? how to apply this ???
  std::transform( str.begin(), str.end(), str.begin(), (int(*)(int)tolower );
  //result: "abcäöüabcäöü"
  </code></pre>
  
  <p>The characters ÄÖÜ and äöü (it's like Ae, Oe, Ue) will not be converted correctly.</p>
  
  <p>P.S.: I don't prefer a big switch <em>sweat</em> and also I know BOOST is capable of everything, i would prefer a STL solution.  </p>
  
  <p>thanks in advance<br>
  Oops</p>