Resolves the C + + code in eclipse to display the symbol & #39;std& #39; Could not being resolved problem

The first time I wrote C + + code in Eclipse, I wrote a simple Hello world program, not yet waiting for me to compile. All sorts of errors were reported, but the code was so simple. How could there be so many mistakes. So I did not bother. After the compilation is executed, it can output normally!!! Hello World!!!, but I still have a lot of red forks in my code, and I put the mouse on it: Symbol ' std ' could not being resolved this information.

So the question came. How to solve?

Method: After writing the library function, save it immediately. Then the code will not be able to error.

Like:--> first write # include <iostream>

-Save

-and then write the following code (only if the correct is not an error)

Resolves the C + + code in eclipse to display the symbol & #39;std& #39; Could not being resolved problem