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c   Object array initialization without default constructor
#include <iostream>
class Car
{
private:
  Car(){};
  int _no;
public:
  Car(int no)
  {
    _no=no;
  }
  void printNo()
  {
    std::cout<<_no<<std::endl;
  }
};
void printCarNumbers(Car *cars, int length)
{
    for(int i = 0; i<length;i++)
         std::cout<<cars[i].printNo();
}

int main()
{
  int userInput = 10;
  Car *mycars = new Car[userInput];
  for(int i =0;i < userInput;i++)
         mycars[i]=new Car[i+1];
  printCarNumbers(mycars,userInput);
  return 0;
}

cartest.cpp: In function ‘int main()’:
cartest.cpp:5: error: ‘Car::Car()’ is private
cartest.cpp:21: error: within this context

#include <iostream>
#include <vector>

class Car
{
private:
    Car(); // if you don't use it, you can just declare it to make it private
    int _no;
public:
    Car(int no) :
    _no(no)
    {
        // use an initialization list to initialize members,
        // not the constructor body to assign them
    }

    void printNo()
    {
        // use whitespace, itmakesthingseasiertoread
        std::cout << _no << std::endl;
    }
};

int main()
{
    int userInput = 10;

    // first method: userInput copies of Car(5)
    std::vector<Car> mycars(userInput, Car(5));

    // second method:
    std::vector<Car> mycars; // empty
    mycars.reserve(userInput); // optional: reserve the memory upfront

    for (int i = 0; i < userInput; ++i)
        mycars.push_back(Car(i)); // ith element is a copy of this

    // return 0 is implicit on main's with no return statement,
    // useful for snippets and short code samples
}

void printCarNumbers(Car *cars, int length)
{
    for(int i = 0; i < length; i++) // whitespace! :)
         std::cout << cars[i].printNo();
}

int main()
{
    // ...

    printCarNumbers(&mycars[0], mycars.size());
}

class Car {
    int _no;
public:
    Car( int no ) :_no( no ) {
    }
};

int main() {
    void* raw_memory = operator new[]( NUM_CARS * sizeof( Car ) );
    Car* ptr = static_cast<Car*>( raw_memory );
    for( int i = 0; i < NUM_CARS; ++i ) {
        new( &ptr[i] )Car( i );
    }
    // destruct in inverse order
    for( int i = NUM_CARS - 1; i >= 0; --i ) {
        ptr[i].~Car();
    }
    operator delete[]( raw_memory );
    return 0;
}

static Car*  Car::CreateCarArray(int dimensions)

#define DEFAULT_CAR_INIT 0
Car::Car(int _no=DEFAULT_CAR_INIT);

Car *c = (Car*) malloc(sizeof(Car) *userInput);

Car** mycars = new Car*[userInput];
for (int i=0; i<userInput; i++){
    mycars[i] = new Car(...);
}

...

for (int i=0; i<userInput; i++){
    delete mycars[i];
}
delete [] mycars;

static Car* makeArray(int length){
    return new Car[length];
}

Car* createCars(unsigned number)
{
    if (number == 0 )
        return 0;
    Car* cars = reinterpret_cast<Car*>(new char[sizeof(Car)* number]);
    for(unsigned carId = 0;
        carId != number;
        ++carId)
    {
        new(cars+carId) Car(carId);
    }
    return cars;
}