In order to create an array of ints dynamically, I need to do int *a = new int[20];.
Is there a similar way to create an array of objects or structs?
For example, I need a dynamically allocated array of objects of class A, how should I declare it(Syntax)?
What constructor would be called on each object(if at all any constructor is called)?
Using arrays with pointer:
A* a = new A [20];
Without pointers
A a [20];
I suggest to use vectors:
//init
std::vector<A> aList;
//reserve memory size - not necessary
aList.reserve (20);
//put elements in
aList.push_back (A ());
//access elements
aList [0];
You can do it using this line:
A* a = new A[N];
How it works?
the new keyword will allocate N sequential block in the heap. Each block has a size of sizeof(A) so the total size in bytes is N*sizeof(A). Allocating those objects in memory is ensured done by calling the default constructor N times.
Alternative:
Use std::vector instead. It will do all the work for you.
Syntax(c++):
ClassName *classObject = new ClassName;
For example, Let's assume a class called car.
car *obj = new car;
car *obj = new car[n]; // n objects will be created by calling the def. constructor
A* a = new A[20];, and the default ctor will be called.std::vectorinstead ofnewexpression?std::vector. But How does it actually work?