Help με C++!!!

Loipon.
Tha parakalousa opoion mporei na rijei mia matia gia na mou pei pws diorthonete to error pou mou bgazei gia enan operator.

parathetw kai ta links tou header file pou parousiazei to problhma.An xreiazontai kai ta upoloipa komatia tou project mporw na ta anebasw.
Thanx prokatabolika.

Three_vector.h

Και to error pou bgazei o compiler:.In file included from calcAcc.cpp:1:
three_vector.h:1:20: iostream: No such file or directory

In file included from calcAcc.cpp:1:
three_vector.h:9: error: ISO C++ forbids declaration of `ostream' with no type
three_vector.h:9: error: `ostream' is neither function nor member function; cannot be declared friend
three_vector.h:9: error: expected `;' before '&' token

make.exe: *** [calcAcc.o] Error 1

Mas exei anevasei lathos arxeio. Mas edoses to three_vector.cpp eno ta lathi sou einai sto three_vector.h

Kapsame flatza....


three_vecto.h(swsto)

I friend xrisimopieitai kata ti dilosi sinartiseon i klaseon... Opote ti kanei ekei pera sti grammi 9???