Return a pointer to an array

Suppose you have a class with a private pointer to an array. How can you use a getter to access (or effectively copy the data) so you can access it in a different variable.

class MyClass
{
   private:
      double *x;
   public:
      myClass();
      virtual ~MyClass(开发者_StackOverflow中文版);
      double* getX() const;
      void setX(double* input);
};

MyClass::MyClass()
{
   double foo[2];
   double * xInput;
   foo[0] = 1;
   foo[1] = 2;

   xInput = foo;
   setX(xInput);
}

void MyClass::setX(double * input)
{
   x = input;
}

double * MyClass::getX() const;
{
   return x;
}

int main()
{
   MyClass spam(); // Construct object
   double * bar = spam.getX(); // This doesn't work
}

In this case, bar[0] and bar[1] are equal to jibberish: -9.2559631349317831e+061.

MyClass spam(); // Construct object

That does not construct an object, that declares a function called spam that takes no arguments and returns a MyClass. This default constructs an object:

MyClass spam; // Construct object

For more information google the most vexing parse.

Update: As @Mark Ransom pointed out, there is another problem with your code. In your constructor you create an array, and then set x to point to such array. However the array lifetime ends once the constructor finishes execution, so further access to x would crash (if you are lucky enough).

Just a guess, the program is crashing or showing the wrong output. This is because the constructor is setting a pointer to a local array, which leaves scope and gets destroyed at the end of the constructor.

That should probably be *bar instead of bar[0].