// compile using 
// g++  -std=c++0x -Wall C++11_factorial.cpp
#include<iostream>
#include<vector>
using namespace std;

long int constexpr factorial (int n)
{
  // only one return statement is allowed; use ternary operator ?
    return n > 0 ? n * factorial( n - 1 ) : 1;
}

int main()
{
  vector<long int> fact;
  constexpr long int fact13=factorial(13); // computed at compile time   

  for (int i=1; i<30;++i) { 
    fact.push_back(factorial(i)); // use factorial as usual
  }
  cout <<"factorial\n";
  for( auto f: fact) { cout << f << endl;}
  cout<<"Warning: large n factorials are wrong\n";
  cout<<fact13<<endl;

}

/* if you compile this using 
 g++  -S -std=c++0x -Wall C++11_factorial.cpp
 you have the file C++11_factorial.s 
 It contains the lines like 
        ....
	movl	$_ZSt4cout, %edi
	call	_ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc
	movabsq	$6227020800, %rsi
	movl	$_ZSt4cout, %edi
	call	_ZNSo9_M_insertIlEERSoT_
        ...
 so notice the number 6227020800, which is 13! 
*/