title: C++ #include <iostream>
body: <p>I'm a complete newbie to C++. I'm trying to write a simple c++
  program but I got an error message. I suspect this is due to me
  accidentally deleting some .h files on my mac which might have ruined
  my Clang compiler. How can I fix this? Do I need to reinstall Xcode or
  change a compiler?</p>
  
  <p>Error message from terminal:</p>
  
  <pre><code>    192:desktop ivanlee$ gcc test.cpp
      In file included from test.cpp:1:
      In file included from /Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/iostream:38:
      In file included from /Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/ios:215:
      In file included from /Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/iosfwd:90:
      In file included from /usr/include/wchar.h:70:
      In file included from /usr/include/_types.h:27:
      /usr/include/sys/_types.h:32:10: fatal error: 'sys/cdefs.h' file not found
          #include &lt;sys/cdefs.h&gt;
               ^
      1 error generated.
  </code></pre>
  
  <p>Code:</p>
  
  <pre><code>#include &lt;iostream&gt;
  
  int main(){
      return 0;
      std::cout &lt;&lt; "Hey";
  }
  </code></pre>