why we use <iostream. h>?

Answer 1

<iostream> and <iostream.h> contains methods such as cin, cout, cerr and the others.

<iostream.h> was more commonly used by C++98 and earlier, however, after C++03, it completely disappeared. So we no longer use it or need it. <iostream> is more than enough

Answer 2

<iostream.h> is obsolete. Modern compilers recognise <iostream>

Answer 3

we include it to be able to use things like cout, cin etc. They are not built in by default.

Answer 4

thnks jay