为什么要变成iostream

[han_v]

我是个菜鸟，在visual C++6.0中编译通不过，提示：
E:\VC\31\31.cpp(7) : error C2679: binary '>>' : no operator defined which takes a right-hand operand of type 'class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >' (or there is no acceptable conversion)
E:\VC\31\31.cpp(8) : error C2679: binary '<<' : no operator defined which takes a right-hand operand of type 'class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >' (or there is no acceptable conversion)

#include<iostream.h>
#include<string>
using namespace std;
int main()
{
string str;
cin>>str;
cout<<"I tlak:"<<str<<endl;
cout<<"Hello!"<<endl;
cout<<"hello!"<<endl;
cout<<"This is test1."<<endl;
return 0;
}

而把头文件#include<iostream.h>改成#include<iostream>就ok了，请问是为什么啊？

[insulted]

请参考这个
http://blog.csdn.net/hairetz/archive/2009/05/14/4184385.aspx