title: How to convert AnsiString to UnicodeString in Delphi XE4
body: <pre><code>exzample code:
  var
    str1 : String;
    str2 : AnsiString;
    ....
    str2 := ....;
    str1 := String(str2);  
  </code></pre>
  
  <p>I converted such as above,but it didn't work.i found that some data lost in str1.is there a safe way to convert AnsiString to UnicodeString?</p>