摘自C/C++ Reference的FAQ，有点意思

Some of the examples on this site don't work on my system. What's going on?

Most of the code on this site was compiled under ( or ) with the . Since this site is merely a reference for the , (check , too) not every compiler will support every function listed here. For example,

• Header files change like mad. To include the necessary support for , you might have to use any of these:

  #include 
  #include 
  #include 
  

  (according to the spec, the first of those should work, and the compiler should know enough to use it to reference the real vector header file.)
• Another header file issue is that newer compilers can use a more platform-independent commands to include standard C libraries. For example, you might be able to use

  #include 
  

  instead of

  #include 
  

• All of the code on this site assumes that the correct namespace has been designated. If your compiler is a little old, then you might be able to get away with using simple statements like:

        cout << "hello world!";
  

  However, newer compilers require that you either use

        std::cout << "hello world!";
  

  or declare what namespace to use with the "using namespace" command.
• Certain popular compilers (like the one shipped with Microsoft's Visual C++) have alternative or additions to the C++ Standard Template Library. For example, the MFC in Visual C++ provides you with the string type "CString", which has string functionality but is not part of the C++ STL.

...The list goes on and on. In other words, individual results may vary.