When are copy constructors called? | Constructor in C++

A copy constructor is defined by the programmer or by compiler itself. A call to copy constructor is embedded under the following three conditions:
1. When an object is created and at the same time equated to some other existing object.
 For example:

A A1; //default constructor called.

A A2=A1; //copy constructor called.

(or)

A A2(A1) //copy constructor called.

(or)

A *Aptr= new A(A1); //copy constructor called.

2. When an object is created without having the reference of the argument, then the copy constructor is called by default for the argument object.

For example:

A A1;

xyz(A1);

void xyz(A A2)

{

//defination of xyz()

}

3. When an object is created and at the same time equated to a call to a function that returns an object.

For example:

A xyz();

{

A A1; //remaining defination of xyz();

return A1;

}

A A2=xyz();