#include <iostream> and std relation

Question

hi to all im beginner in c++ programming
when I read some sources tell me std is name space which contain function cout or cin
what is rule of #include <iostream>
its called as header what relation exist between header and name space

Answer 1

There is no direct relation between header file and namespace.
A header file is file is a file containing the declaration of your functions/classes i.e. their signatures (interfaces)

A namespace is mainly use to avoid name collision by grouping functions/classes of the same "group" under a common name
std for the standard library, boost for boost, etc ...

Answer 2

so classes and fucntion are parts of namespace
i mean every name space has class and function?
if so why we need header file ?
becuse every time we can notice to class or functon by call it namespace
still have problem in file header excusme im beginer

Answer 3

i use code block can you tell me how to find property of header file with opening it in code block