I'm trying to hold the screen on my output using the header file <iostream.h>, but I don't know any equivalent function to the getch() & clrscr() functions of <conio.h> in <iostream.h> or any other C++ library. Are there any such functions?
if you work on windows you can use system("pause"), this will give you "press any key to continue" message.
The conio.h functions are compiler extensions to the language, not part of C or C++. There isn't a direct replacement in standard C++.
For getch(), int ch = std::cin.get(); is probably the closest equivalent -- but bear in mind that this will read from buffered standard input, whereas I think the conio.h getch does an unbuffered read.
Any implementation of clrscr() is going to be very platform-dependent -- not all screens or terminals have a notion of clearing, and those that do have wildly differing ways to access that functionality.
If you need to treat the terminal as something other than a set of character streams, your best bet is probably to look for a library which hides the details of the underlying terminal, screen or console from you. If you're on a UNIXish system, look at the curses or ncurses library; I don't know of any suggestions for other OSes.