来帮菜鸟看一小下下哈！
#include <iostream>
#include <string>
using std::cout;
using std::endl;


int main()
{
string st( "The expense of spirit\n ");
cout < < "The size of " < < st < < "is " < <st.size()
< < "characters,including the newline " < <endl;
return 0;
}


编译错误提示：

--------------------Configuration: Text2 - Win32 Debug--------------------
Compiling...
Text2.cpp
C:\Program Files\我的文档\我的视频\Text2.cpp(9) : error C2065: 'string ' : undeclared identifier
C:\Program Files\我的文档\我的视频\Text2.cpp(9) : error C2146: syntax error : missing '; ' before identifier 'st '
C:\Program Files\我的文档\我的视频\Text2.cpp(9) : error C2065: 'st ' : undeclared identifier
C:\Program Files\我的文档\我的视频\Text2.cpp(10) : error C2228: left of '.size ' must have class/struct/union type
执行 cl.exe 时出错.

Text2.exe - 1 error(s), 0 warning(s)


why?how can i do?

[解决办法]
using std::cout;
using std::endl;

把这两句换成
using namespace std;