Where to use iostream, conio, <stdio.h>

Answer 1

stdio.h is a header file
we can use functions from library like scanf...
conio.h enables us to use functions like clscr

Answer 2

I want to know too

Answer 3

iostream is used in c++
i - input , o - output objects such as cin cout are available in this header

stdio is used in c
it means standard input output
scanf, printf are available in this header

conio can be used with both c&c+
some functions like clear screen, getch(),getche().. are available in this header...