title: How to include a .h file correctly in VC++?
body: <p>I have a very simple C++/CLI window form program which is 100% working alright.</p>
  
  <p>Since I want to add call internet explorer when I click a button on my window form, I add "ONE LINE of code" for testing purpose.</p>
  
  <p>I add <strong>#include "Shellapi.h"</strong> under <strong>#pragma once</strong>. After that, VS gives me 500 lines of an error message.</p>
  
  <p>My question is that I am only adding a .h file into my program. Why there will cause any problem? Do I miss something?</p>
  
  <p>===========The first few lines of the error message===============</p>
  
  <pre><code>1&gt;C:\Program Files\Microsoft SDKs\Windows\v7.0A\include\Shellapi.h(56): error C2065: 'HDROP' : undeclared identifier
  1&gt;C:\Program Files\Microsoft SDKs\Windows\v7.0A\include\Shellapi.h(56): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
  1&gt;C:\Program Files\Microsoft SDKs\Windows\v7.0A\include\Shellapi.h(59): error C2146: syntax error : missing ';' before identifier 'DECLSPEC_IMPORT'
  1&gt;C:\Program Files\Microsoft SDKs\Windows\v7.0A\include\Shellapi.h(59): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
  1&gt;C:\Program Files\Microsoft SDKs\Windows\v7.0A\include\Shellapi.h(59): error C2146: syntax error : missing ';' before identifier 'UINT'
  1&gt;C:\Program Files\Microsoft SDKs\Windows\v7.0A\include\Shellapi.h(59): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
  1&gt;C:\Program Files\Microsoft SDKs\Windows\v7.0A\include\Shellapi.h(59): error C2146: syntax error : missing ';' before identifier 'STDAPICALLTYPE'
  1&gt;C:\Program Files\Microsoft SDKs\Windows\v7.0A\include\Shellapi.h(59): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
  </code></pre>