C/C++ - Problema con iostream ed il gcc

Premetto che programmo in C++ da poco e per motivi scolastici mentre il C ed altri linguaggi li conosco decentemente. Il mio OS è Ubuntu 12 ed il mio compiulatore il gcc. Il programma è questo

 
#include <iostream>

using namespace std;

main(){
  int a,b,c;
  cout<<"Inserisci A: ";
  cin>>a;
  cout<<"Inserisci B: ";
  cin>>b;
  cout<<"Inserisci C: ";
  cin>>c;
  int max=a;
  if (b>max) max = b;
  if (c>max) max = c;
  cout<<max<<"\n\n";
}

Appena provo a compilarlo il messaggio è il seguente

Massimo.cpp:5:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type]
/tmp/ccFaS7rV.o: In function `main':
Massimo.cpp:(.text+0xe): undefined reference to `std::cout'
Massimo.cpp:(.text+0x13): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)'
Massimo.cpp:(.text+0x1f): undefined reference to `std::cin'
Massimo.cpp:(.text+0x24): undefined reference to `std::basic_istream<char, std::char_traits<char> >::operator>>(int&)'
Massimo.cpp:(.text+0x2e): undefined reference to `std::cout'
Massimo.cpp:(.text+0x33): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)'
Massimo.cpp:(.text+0x3f): undefined reference to `std::cin'
Massimo.cpp:(.text+0x44): undefined reference to `std::basic_istream<char, std::char_traits<char> >::operator>>(int&)'
Massimo.cpp:(.text+0x4e): undefined reference to `std::cout'
Massimo.cpp:(.text+0x53): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)'
Massimo.cpp:(.text+0x5f): undefined reference to `std::cin'
Massimo.cpp:(.text+0x64): undefined reference to `std::basic_istream<char, std::char_traits<char> >::operator>>(int&)'
Massimo.cpp:(.text+0x90): undefined reference to `std::cout'
Massimo.cpp:(.text+0x95): undefined reference to `std::basic_ostream<char, std::char_traits<char> >::operator<<(int)'
Massimo.cpp:(.text+0xa2): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)'
/tmp/ccFaS7rV.o: In function `__static_initialization_and_destruction_0(int, int)':
Massimo.cpp:(.text+0xd0): undefined reference to `std::ios_base::Init::Init()'
Massimo.cpp:(.text+0xd5): undefined reference to `std::ios_base::Init::~Init()'
collect2: ld returned 1 exit status

provando a togliere le riga "using namespace std;" ottengo un altro errore:

Massimo.cpp:3:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type]
Massimo.cpp: In function ‘int main()’:
Massimo.cpp:5:3: error: ‘cout’ was not declared in this scope
Massimo.cpp:5:3: note: suggested alternative:
/usr/include/c++/4.6/iostream:62:18: note:   ‘std::cout’
Massimo.cpp:6:3: error: ‘cin’ was not declared in this scope
Massimo.cpp:6:3: note: suggested alternative:

la libreria iostream serve per le funzioni cin e cout. Come detto conosco il C e non avrei problemi personalmente ad usare printf e scanf, ma il mio professore non credo capisca molto l'argomento (provate a spiegargli cos'è Linux...) e quindi vuole proprio che si faccia a modo suo.
Quindi come faccio a includere iostream e compagnia bella?

Prova con questo codice:

#include <iostream>

int main ( void )
{
    int a, b, c;

    std::cout << "Inserisci A: ";
    std::cin >> a;

    std::cout << "Inserisci B: ";
    std::cin >> b;

    std::cout << "Inserisci C: ";
    std::cin >> c;

    int max = a;
    
    if ( max < b )
        max = b;

    if ( max < c )
        max = c;

    std::cout << "Il numero massimo è: " << max;

    return 0;
}

Dimmi se funziona... a me funge

/tmp/ccxgby6t.o: In function `main':
Massimo.cpp:(.text+0xe): undefined reference to `std::cout'
Massimo.cpp:(.text+0x13): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)'
Massimo.cpp:(.text+0x1f): undefined reference to `std::cin'
Massimo.cpp:(.text+0x24): undefined reference to `std::basic_istream<char, std::char_traits<char> >::operator>>(int&)'
Massimo.cpp:(.text+0x2e): undefined reference to `std::cout'
Massimo.cpp:(.text+0x33): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)'
Massimo.cpp:(.text+0x3f): undefined reference to `std::cin'
Massimo.cpp:(.text+0x44): undefined reference to `std::basic_istream<char, std::char_traits<char> >::operator>>(int&)'
Massimo.cpp:(.text+0x4e): undefined reference to `std::cout'
Massimo.cpp:(.text+0x53): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)'
Massimo.cpp:(.text+0x5f): undefined reference to `std::cin'
Massimo.cpp:(.text+0x64): undefined reference to `std::basic_istream<char, std::char_traits<char> >::operator>>(int&)'
Massimo.cpp:(.text+0x90): undefined reference to `std::cout'
Massimo.cpp:(.text+0x95): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)'
Massimo.cpp:(.text+0xa2): undefined reference to `std::basic_ostream<char, std::char_traits<char> >::operator<<(int)'
/tmp/ccxgby6t.o: In function `__static_initialization_and_destruction_0(int, int)':
Massimo.cpp:(.text+0xd0): undefined reference to `std::ios_base::Init::Init()'
Massimo.cpp:(.text+0xd5): undefined reference to `std::ios_base::Init::~Init()'
collect2: ld returned 1 exit status

Allora un codice C++ si compila con g++ e non gcc. gcc è per il c.
Poi hai fatto un piccolo errore, hai dimenticato "int " davanti a main.
Compila così con g++:
g++ file.cpp -o file.out

#include <iostream>
using namespace std;
 
int main(){
  int a,b,c;
  cout<<"Inserisci A: ";
  cin>>a;
  cout<<"Inserisci B: ";
  cin>>b;
  cout<<"Inserisci C: ";
  cin>>c;
  int max=a;
  if (b>max) max = b;
  if (c>max) max = c;
  cout<<max<<"\n\n";
}

proverò con il g++. Grazie mille.

ps
Quello dell'int davanti al main lo sapevo, ma il prof aveva detto di fare così...

Ora ho provato e va tutto bene. Compilazione perfietta.