Question

I would like to know is possible to create arrays as user requires. For example

1. I ask the user “Do you want coffee”
   2.if the user say yes and i create a array of coffee object.
   …..
2. I ask the user “Do you want to have another coffee”?
3. if user say yes than i create another array of coffee class
   if not i dont create.

Is this achieveable or must i create a fixed number of array?

Answer 1

You cannot create fixed size array at runtime in C++, except some compilers (like g++) provides extension for VLA.

Use std::vector instead. It grows as per your control and automatically deallocates itself when requirement is done.

Edit: As the std::vector cannot be used by the asker, following is the way using new[] with ‘some’ pseudo code:

Coffee **pQuestions = new Coffee* [n]; // n - number of times coffee is asked
for(uint i = 0; i < N; ++i)
{
  /* ask for Coffee */
  if(/* yes */)
    pQuestion[i] = new Coffee[size]; // whatever array size you want
}

^{Here n and size are variables(can or cannot be constants) as per your need}

Later when you are done, deallocate all the memory as delete[] pQuestions[i]; and delete[] pQuestions;.