i am been reading a book and code in this book is always #include<iostream.h>, i tried to use that and it gives the error message. also in this book they use void main instead of int main.
"iostream.h" is a header used with C, not C++. Also, if a books uses "void main()" in favour of "int main()", then I'd quite literally throw the book into the bin; a tree died for that stool.
I recommend acquiring a decent book with a good reputation, such as "C++ Primer 4th Ed.", or, "The C++ Programming Language" by Bjarne Stroustrup.