Create array of object as user requirement increase?

Question

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

I ask the user "Do you want coffee" 2.if the user say yes and i create a array of coffee object. .....
I ask the user "Do you want to have another coffee"?
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?

score 2 · Accepted Answer · edited May 23 '17 at 10:24

2

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;.

edited May 23 '17 at 10:24

Community

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answered Oct 05 '12 at 04:56

iammilind

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int * myArray = new int[5]; // creating a fixed-size array at runtime in C++? – Jeremy Friesner Oct 05 '12 at 05:30
@JeremyFriesner, no that's not fixed sized array. It's a dynamic array similar to `std::vector`; only syntactical difference is that `new[]` returns a raw pointer. Internally `std::vector` does `new[]` and lot more things. – iammilind Oct 05 '12 at 05:47
I cant use vector. I need to use array only. – rasul1719435 Oct 05 '12 at 08:26
@iammilind can u explain abit further, sample codes may be please. – rasul1719435 Oct 05 '12 at 08:39

score 0 · Answer 2 · answered Oct 05 '12 at 04:56

You can use standard container classes like std::vector which gives you resizeable vectors of some arbitrary but given type. Of course, you can have vectors of vectors, or vectors of queues, etc.

^{(You could use manually allocated pointers and code à la C, but you'll better use the powerful containers provided by the STL).}

Create array of object as user requirement increase?

2 Answers2