PHP Extension - how can i use iostream in vc2008?

Hi.
I created a new php-extension.
I did nothing but just write "#include <string>" int the php-extension source file,the vs2008 showed me such msgs.

1>c:\program files\microsoft visual studio 9.0\vc\include\ostream(967) : error C2491: “std::endl”: definition of dllimport function not allowed
1>c:\program files\microsoft visual studio 9.0\vc\include\ostream(976) : error C2491: “std::endl”: definition of dllimport function not allowed
1>c:\program files\microsoft visual studio 9.0\vc\include\ostream(985) : error C2491: “std::ends”: definition of dllimport function not allowed
1>c:\program files\microsoft visual studio 9.0\vc\include\ostream(993) : error C2491: “std::ends”: definition of dllimport function not allowed
1>c:\program files\microsoft visual studio 9.0\vc\include\ostream(1001) : error C2491: “std::flush”: definition of dllimport function not allowed
1>c:\program files\microsoft visual studio 9.0\vc\include\ostream(1009) : error C2491: “std::flush”: definition of dllimport function not allowed
1>c:\program files\microsoft visual studio 9.0\vc\include\istream(1068) : error C2491: “std::ws”: definition of dllimport function not allowed
1>c:\program files\microsoft visual studio 9.0\vc\include\istream(1103) : error C2491: “std::ws”: definition of dllimport function not allowed

I can use std::string in php-extension with gcc, what`s wrong with vc?