title: C++ tolower/toupper char pointer
body: <p>Do you guys know why the following code crash during the runtime?</p>
  
  <pre><code>char* word;
  word = new char[20];
  word = "HeLlo"; 
  for (auto it = word; it != NULL; it++){        
      *it = (char) tolower(*it);
  </code></pre>
  
  <p>I'm trying to lowercase a char* (string). I'm using visual studio.</p>
  
  <p>Thanks</p>