Dynamic memory allocation

new & delete

new (operator) has 2 steps:

• allocate space
• call the constructor function

C++

int *p1 = new int // malloc(sizeof(int)); + constructor
int *p2 = new int [10] // continuous space allocated

delete + pointer

If delete a constructed type, it will implement D’tor function

C++

p2 = new student [10];
delete p2; // remove the first one
delete[] p2; // remove whole 10 objects

it is safe to delete a NULL.

Copy constructor

has a unique signature

C++

T::T(const T&)

call by reference

compiler (in-line) would do it automatically.

But how?

• member-wise (versus bit-wise)

if it has a class defined, it will iteratively call its copy function.

It is neccesary to define a copy constructor when you have pointer member or what you don't want to be copied in your class.

C++

A b(a);
A c = a;

// define function passing in value
void f(A aa)
{

}

// return value
A f()
{
  A aa(19);
  return aa;
}

Assignment: can be done alot of time. Ctor can only be called once.