GCC and package installation
 

When i use #include<iostream> ingcc, I am given an error saying no such files exist

How do i rectify it??

Secondly
How come i tell if I have a specific package installed or a particular library installed

if your distro is rpm based
#rpm -qa | grep gcc

#include <iostream>

'iostream' is a c++ header, and is provided
by the package 'libstdc++6-4.3-dev' being
installed with the 'g++-4.3' package.
( I guess, you are still using Debian 5.)

1) su
2) apt get-install g++
( which will install g++-4.3 )
Or choose another or some more 'g++'s, if you wish,
they are all mentioned here
http://packages.debian.org/lenny/g++
http://packages.debian.org/lenny/g++-4.3
.....