title: How to copy part of CString to a new one?
body: <p>I got a <code>CString str</code></p>
  
  <p>I want to copy <code>str[3]~ str[5]</code> to a brand new one.
  I tried C++ char* 's method, not compatible.</p>
  
  <p>So what is the right way do this in VC++</p>
  
  <p>Thank you,</p>