why we do not use .h after iostream

cuz i believe this is for old compilers or for C/C# we are dealing with C++ here a new version too

if you don't writes it then also it works

The compiler automatically puts .h if it doesn't exist.

remember, if you want.. #include<iostream> then always write after using namespace std; this line. otherwise, if you are written.. #include<iostream.h> then no need above line. in short, without header .ext file you must need that line unless simple it. thank you.