Default constructor for a stack

[gameboy1995]

I am currently working on a project for class that requires us to implement a stack for integer use as a calculator. I am having problems with my default constructor and am wondering what I am missing.

  OperandStack(int stackSize)
	{
		if (stackSize<=0)
			{cout<<"Must be positive"<<endl;}
		this->capacity=capacity;
		s =new double[stackSize];
		t=0;
	}

Thank you for your assistance.

[MiiNiPaa]

this->capacity=capacity; What do you think this line is doing?
Shouldn't it be this->capacity = stackSize;?

Also prefer to make errorneous data impossible to pass and use member init lists.

OperandStack(std::size_t stackSize) : capacity(stackSize), s(new double[stackSize]), t(0) : 
{}