Page 208 - DCAP404 _Object Oriented Programming

Unit 9: Inheritance

The constructors for virtual base classes are invoked before any non-virtual base classes. If there Notes
are multiple virtual base classes, they are invoked in the order in which they are declared. Any
non-virtual bases are then constructed before the derived class constructor is executed.
Table 9.1: Execution of base Class Constructors

Methods of Inheritance Order of execution
Class X: public y { }; Y( ); base constructor
X ( ); derived constructor
Class X: public y, public Z Y( ); base constructor (first)
{ }; Z( ); base constructor (second)
X( ); derived constructor
Class X: public Y, virtual public Z Z( ); virtual base constructor
{ }; Y ( ); ordinary base constructor
X( ); derived constructor

Let us consider a program using constructors:
# include <iostream.h>

class A
{
int a1;
public:
A (int x)
{
a1 = x:

cout << “constructor of A\n”;
}
void display (void)
{
cout << “a1 = “ << a1 << “\n”;
}
}
class B
{

float b1;
public:
B( float y)
{
b1 = y;
cout << “ constructor of B\n”;
}

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