How to declare array with auto

Question

I have been playing with auto and I noticed that for most cases you can replace a variable definition with auto and then assign the type.

I

Answer 1

decltype works with g++ 4.9.0 20130601 for this:

#include 
#include 

static std::ostream& logger = std::clog;

class A {
    static int _counter;
    int _id;
  public:
    A() : _id(++_counter) {
        logger << "\tA #" << _id << " c'tored\n";
    } 

    ~A() {
        //logger << "\tA #" << _id << " d'tor\n";
    } 

    inline int id() const{
        return _id;
    }
};
int A::_counter(0); 

std::ostream& operator<<(std::ostream& os, const A& a) {
    return os << a.id();
}

int main() {

    auto dump = [](const A& a){ logger << a << " ";};

    logger << "x init\n";
    A x[5]; 
    logger << "x contains: "; std::for_each(x, x+5, dump);

    logger << "\ndecltype(x) y init\n";
    decltype(x) y;
    logger << "y contains: ";  std::for_each(y, y+5, dump);
    logger << std::endl;

    return 0;
}

Output:

x init
    A #1 c'tored
    A #2 c'tored
    A #3 c'tored
    A #4 c'tored
    A #5 c'tored
x contains: 1 2 3 4 5 
decltype(x) y init
    A #6 c'tored
    A #7 c'tored
    A #8 c'tored
    A #9 c'tored
    A #10 c'tored
y contains: 6 7 8 9 10