title: Matching file name using regex in C++
body: <p>I want to match a file name using regex in C++. The form of the desired file name is 
  "ProjectXX.txt" where X should be a digit. The code with the regex I use looks:</p>
  
  <pre><code>static const wregex initFile(L"(\\Project)(\\d\\d)\\.(\\txt)");
  wsmatch result;
  if(regex_match(fileName, result, initFile)) 
  </code></pre>
  
  <p>I need <code>CString</code> (therefore <code>L""</code>) since I use windows.h. However the code throws an exception and although I tried to modify the regex, I could not manage it to match the file name. What is the correct regular expression?</p>