It is a feature in c++ to minimize name collisions in the global name space.
This namespace keyword assigns a distinct name to a library that allows other
libraries to use the same identifier names without creating any name collisions.
Furthermore, the compiler uses the namespace signature for differentiating the
What is the use of ‘using’ declaration.
A using declaration makes it possible to use a name from a namespace without the
What is an Iterator class?
A class that is used to traverse through the objects maintained by a container
class. There are five categories of iterators:
Ø input iterators,
Ø output iterators,
Ø forward iterators,
Ø bidirectional iterators,
Ø random access.
An iterator is an entity that gives access to the contents of a container object
without violating encapsulation constraints. Access to the contents is granted
on a one-at-a-time basis in order. The order can be storage order (as in lists
and queues) or some arbitrary order (as in array indices) or according to some
ordering relation (as in an ordered binary tree). The iterator is a construct,
which provides an interface that, when called, yields either the next element in
the container, or some value denoting the fact that there are no more elements
to examine. Iterators hide the details of access to and update of the elements
of a container class.
The simplest and safest iterators are those that permit read-only access to the
contents of a container class. The following code fragment shows how an iterator
might appear in code:
while x/=none do
In this example, cont_iter is the name of the
iterator. It is created on the first line by instantiation of cont_iterator
class, an iterator class defined to iterate over some container class, cont.
Succesive elements from the container are carried to x. The loop terminates when
x is bound to some empty value. (Here, none)In the middle of the loop, there is
s(x) an operation on x, the current element from the container. The next element
of the container is obtained at the bottom of the loop.
List out some of the OODBMS available.
Ø GEMSTONE/OPAL of Gemstone systems.
Ø ONTOS of Ontos.
Ø Objectivity of Objectivity inc.
Ø Versant of Versant object technology.
Ø Object store of Object Design.
Ø ARDENT of ARDENT software.
Ø POET of POET software.
List out some of the object-oriented
Ø Object Oriented Development (OOD) (Booch 1991,1994).
Ø Object Oriented Analysis and Design (OOA/D) (Coad and Yourdon
Ø Object Modelling Techniques (OMT) (Rumbaugh 1991).
Ø Object Oriented Software Engineering (Objectory) (Jacobson
Ø Object Oriented Analysis (OOA) (Shlaer and Mellor 1992).
Ø The Fusion Method (Coleman 1991).
What is an incomplete type?
Incomplete types refers to pointers in which there is non availability of the
implementation of the referenced location or it points to some location whose
value is not available for modification.
int *i=0x400 // i points to address 400
*i=0; //set the
value of memory location pointed by i.
Incomplete types are otherwise called uninitialized pointers.
What is a dangling pointer?
A dangling pointer arises when you use the address of an object after its
lifetime is over.
This may occur in situations like returning addresses of the automatic variables
from a function or using the address of the memory block after it is freed.
Differentiate between the message and
Objects communicate by sending messages Provides
response to a message.
to each other.
A message is sent to invoke a method.
It is an implementation of an operation.
What is an adaptor class or Wrapper class?
A class that has no functionality of its own. Its member functions hide the use
of a third party software component or an object with the non-compatible
interface or a non- object- oriented implementation.
What is a Null object?
It is an object of some class whose purpose is to indicate that a real object of
that class does not exist. One common use for a null object is a return value
from a member function that is supposed to return an object with some specified
properties but cannot find such an object.
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