What is the relationship between #include<iostream> and using namespace std ?

Answer 1

#include<iostream> is a header, it allows you to use the default library, iostream.
namespace std allows you to call iostream w/o using the keyword 'std' all the time.

Answer 2

try removing "using namespace std" in your codes. run it. Then after that, add "std::" in front of your cout and cin, then you get what I meant.

Answer 3

Thank you Wen Qin.
but i dont really understand how or when i call iostream using the keyword std, i only used cin and cout..

Answer 4

very well! thanks so much!