title: What is _WIN32_WINNT and how does it work?
body: <p><strong>EDIT 2:</strong> Ok so I changed to Orwell DevC++ which contains the "winnt.h" that contains <em>#define KEY_WOW64_64KEY 0x0100</em> but it still is not working. <em>(Refer to EDIT 1:)</em></p>
  
  <p><strong>EDIT 1:</strong> I looked into the "winnt.h" which came along the CodeBlock and DevC++ and the DevC++'s is missing the following lines:</p>
  
  <pre><code>#if (_WIN32_WINNT &gt;= 0x0502)
  #define KEY_WOW64_64KEY 0x0100
  #define KEY_WOW64_32KEY 0x0200
  #endif
  </code></pre>
  
  <p>And putting the above code in the wint.h of DevC++ doesn't work.</p>
  
  <hr>
  
  <p><strong>Original Post:</strong>
  I have a 32bit application (developing in DevC++ and Windows 7 64bit) which reads a 64bit app's registry as one of its task, so I am trying to use "KEY_WOW64_64KEY" flag in RegOpenKeyEx, and found few posts regarding how to use it with _WIN32_WINNT : <a href="https://stackoverflow.com/questions/12528099/error-with-regopenkeyex"><em>this</em></a> and <a href="https://stackoverflow.com/questions/5247862/error-with-regopenkeyex"><em>this</em></a></p>
  
  <p>It worked like charm when I used it in a CodeBlock Project(a test project) but the same code is not working with DevC++, I can't port it to codeblock now since codeblock presents other problems.</p>
  
  <p>How do I make it work with DevC++ ?</p>
  
  <p>Thanks</p>