1. Explain transaction atomicity.
We must ensure that the entire transaction is either
committed or rolled back.
2. Explain consistency.
We must ensure that the system is always left at the correct
state in case of the failure or success of a transaction.
3. Explain integrity.
Ensure data integrity by protecting concurrent transactions
from seeing or being adversely affected by each other's partial and
uncommitted results.
4. Explain durability.
Make sure that the system can return to its original state in
case of a failure.
5. Explain object pooling.
With object pooling, COM+ creates objects and keeps them in
a pool, where they are ready to be used when the next client makes a
request. This improves the performance of a server application that
hosts the objects that are frequently used but are expensive to
create.
6. Explain JIT activation.
The objective of JIT activation is to minimize the amount of
time for which an object lives and consumes resources on the server.
With JIT activation, the client can hold a reference to an object on
the server for a long time, but the server creates the object only
when the client calls a method on the object. After the method call is
completed, the object is freed and its memory is reclaimed. JIT
activation enables applications to scale up as the number of users
increases.
7. Explain role-based security.
In the role-based security model, access to parts of an
application are granted or denied based on the role to which the
callers belong. A role defines which members of a Windows domain are
allowed to work with what components, methods, or interfaces.
8. Explain queued components.
The queued components service enables you to create
components that can execute asynchronously or in disconnected mode.
Queued components ensure availability of a system even when one or
more sub-systems are temporarily unavailable. Consider a scenario
where salespeople take their laptop computers to the field and enter
orders on the go. Because they are in disconnected mode, these orders
can be queued up in a message queue. When salespeople connect back to
the network, the orders can be retrieved from the message queue and
processed by the order processing components on the server.
9. Explain loosely coupled events.
Loosely coupled events enable an object (publisher) to
publish an event. Other objects (subscribers) can subscribe to an
event. COM+ does not require publishers or subscribers to know about
each other. Therefore, loosely coupled events greatly simplify the
programming model for distributed applications.
10. Define scalability.
The application meets its requirement for efficiency even if
the number of users increases.
11. Define reliability.
The application generates correct and consistent information
all the time.
12. Define availability.
Users can depend on using the application when needed.
13. Define security.
The application is never disrupted or compromised by the
efforts of malicious or ignorant users.
14. Define manageability.
Deployment and maintenance of the application is as
efficient and painless as possible.
15. Which namespace do the classes, allowing you to support COM
functionality, are located?
System.EnterpriseServices
16. How do you make a NET component talk to a COM component?
To enable the communication between COM and .NET
components, the .NET Framework generates a COM Callable Wrapper (CCW).
The CCW enables communication between the calling COM code and the
managed code. It also handles conversion between the data types, as
well as other messages between the COM types and the .NET types.
Monday, 28 September 2009
C++ interview questions part1
C++ interview questions
1.What is a modifier?
A modifier, also called a modifying function is a member function that
changes the value of at least one data member. In other words, an
operation that modifies the state of an object. Modifiers are also
known as 'mutators'. Example: The function mod is a modifier in the
following code snippet:
class test
{
int x,y;
public:
test()
{
x=0; y=0;
}
void mod()
{
x=10;
y=15;
}
};
2. What is an accessor?
An accessor is a class operation that does not modify the state of
an object. The accessor functions need to
be declared as const operations
3. Differentiate between a template class and class template. ?
Template class: A generic definition or a parameterized
class not
instantiated until the client provides the needed information. It's
jargon for plain templates. Class template: A class template specifies
how individual classes can be constructed much like the way a class
specifies how individual objects can be constructed. It's jargon for
plain classes.
4. When does a name clash occur?
A name clash occurs
when a name is defined in more than one place. For example., two
different class libraries could give two different classes the same
name. If you try to use many class libraries at the same time, there
is
a fair chance that you will be unable to compile or link the program
because of name clashes.
5. Define namespace.
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 definitions.
6. What is the use of 'using' declaration.
A using declaration makes it possible to use a name from a namespace
without the scope operator.
7. 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: input iterators, output iterators,
forward iterators, bidirectional iterators, 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.
8. List out some of the OODBMS available.
GEMSTONE/OPAL
of Gemstone systems, ONTOS of Ontos, Objectivity of Objectivity Inc,
Versant of Versant object technology, Object store of Object Design,
ARDENT of ARDENT software, POET of POET software.
9. List out some of the object-oriented methodologies.
Object Oriented Development (OOD) (Booch 1991,1994), Object
Oriented Analysis and Design (OOA/D) (Coad and Yourdon 1991), Object
Modelling Techniques (OMT) (Rumbaugh 1991), Object Oriented Software
Engineering (Objectory) (Jacobson 1992), Object Oriented Analysis
(OOA)
(Shlaer and Mellor 1992), The Fusion Method (Coleman 1991).
10. 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.
11. 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. The following
code snippet shows this:
class Sample
{
public:
int *ptr;
Sample(int i)
{
ptr = new int(i);
}
~Sample()
{
delete ptr;
}
void PrintVal()
{
cout << "The value is " << *ptr;
}
};
void SomeFunc(Sample x)
{
cout << "Say i am in someFunc " << endl;
}
int main()
{
Sample s1 = 10;
SomeFunc(s1);
s1.PrintVal();
}
In the above example when PrintVal() function is
called it is called by the pointer that has been freed by the
destructor in SomeFunc.
12. Differentiate between the message and method.
Message:
a. Objects communicate by sending messages to each other.
b. A message is sent to invoke a method.
Method
c. Provides response to a message.
d. It is an implementation of an operation.
13. 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.
14. 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.
15. What is class invariant?
A class invariant is a condition that defines all valid states for an object. It is a logical condition to ensure the correct working of a class. Class invariants
must hold when an object is created, and they must be preserved under
all operations of the class. In particular all class invariants are
both preconditions and post-conditions for all operations or member
functions of the class.
16. What do you mean by Stack unwinding?
It is a process during exception handling when the destructor is called for all local objects between the place where the exception was thrown and
where it is caught.
17. Define precondition and post-condition to a member function.
Precondition: A precondition is a condition that must be true on entry
to a member function. A class is used correctly if preconditions are
never false. An operation is not responsible for doing anything
sensible if its precondition fails to hold. For example, the interface
invariants of stack class say nothing about pushing yet another
element
on a stack that is already full. We say that isful() is a precondition
of the push operation.
Post-condition: A post-condition is a condition
that must be true on exit from a member function if the precondition
was valid on entry to that function. A class is implemented correctly
if post-conditions are never false. For example, after pushing an
element on the stack, we know that isempty() must necessarily hold.
This is a post-condition of the push operation.
18. What are the conditions that have to be met for a condition to be
an invariant of the class?
a. The condition should hold at the end of every constructor.
b. The condition should hold at the end of every mutator (non-const)
operation.
19. What are proxy objects? Objects that stand for other objects are
called proxy objects or surrogates.
template
class Array2D
{
public:
class Array1D
{
public:
T& operator[] (int index);
const T& operator[] (int index)const;
};
Array1D operator[] (int index);
const Array1D operator[] (int index) const;
};
The following then becomes legal:
Array2Ddata(10,20);
cout<
Here data[3] yields an Array1D object
and the operator [] invocation on that object yields the float in
position(3,6) of the original two dimensional array. Clients of the
Array2D class need not be aware of the presence of the Array1D class.
Objects of this latter class stand for one-dimensional array objects
that, conceptually, do not exist for clients of Array2D. Such clients
program as if they were using real, live, two-dimensional arrays. Each
Array1D object stands for a one-dimensional array that is absent from
a
conceptual model used by the clients of Array2D. In the above example,
Array1D is a proxy class. Its instances stand for one-dimensional
arrays that, conceptually, do not exist.
20. Name some pure object oriented languages.
Smalltalk, Java, Eiffel, Sather.
21. Name the operators that cannot be overloaded.
sizeof, ., .*, .- >, ::, ?: Salam in the comments notes that -> can be overloaded.
22. What is a node class?
A node class is a class that, relies on the base class for services and implementation, provides a wider interface to the users than its base class,
relies primarily on virtual functions in its public interface depends on all its direct and indirect base class can be understood only in the context of the base class can be used as base for further derivation can be used to create objects.
A node class is a class that has added new services or functionality
beyond the services inherited from its base class.
23. What is an orthogonal base class?
If two base classes have no overlapping methods or data they are said
to be independent of, or orthogonal to each other. Orthogonal in the
sense means that two classes operate in different dimensions and do
not
interfere with each other in any way. The same derived class may
inherit such classes with no difficulty.
24. What is a container class? What are the types of container
classes?
A container class is a class that is used to hold objects in memory or
external storage. A container class acts as a generic holder. A
container class has a predefined behavior and a well-known interface.
A container class is a supporting class whose purpose is to hide the
topology used for maintaining the list of objects in memory. When a
container class contains a group of mixed objects, the container is
called a heterogeneous container; when the container is holding a
group
of objects that are all the same, the container is called a
homogeneous
container.
1.What is a modifier?
A modifier, also called a modifying function is a member function that
changes the value of at least one data member. In other words, an
operation that modifies the state of an object. Modifiers are also
known as 'mutators'. Example: The function mod is a modifier in the
following code snippet:
class test
{
int x,y;
public:
test()
{
x=0; y=0;
}
void mod()
{
x=10;
y=15;
}
};
2. What is an accessor?
An accessor is a class operation that does not modify the state of
an object. The accessor functions need to
be declared as const operations
3. Differentiate between a template class and class template. ?
Template class: A generic definition or a parameterized
class not
instantiated until the client provides the needed information. It's
jargon for plain templates. Class template: A class template specifies
how individual classes can be constructed much like the way a class
specifies how individual objects can be constructed. It's jargon for
plain classes.
4. When does a name clash occur?
A name clash occurs
when a name is defined in more than one place. For example., two
different class libraries could give two different classes the same
name. If you try to use many class libraries at the same time, there
is
a fair chance that you will be unable to compile or link the program
because of name clashes.
5. Define namespace.
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 definitions.
6. What is the use of 'using' declaration.
A using declaration makes it possible to use a name from a namespace
without the scope operator.
7. 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: input iterators, output iterators,
forward iterators, bidirectional iterators, 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.
8. List out some of the OODBMS available.
GEMSTONE/OPAL
of Gemstone systems, ONTOS of Ontos, Objectivity of Objectivity Inc,
Versant of Versant object technology, Object store of Object Design,
ARDENT of ARDENT software, POET of POET software.
9. List out some of the object-oriented methodologies.
Object Oriented Development (OOD) (Booch 1991,1994), Object
Oriented Analysis and Design (OOA/D) (Coad and Yourdon 1991), Object
Modelling Techniques (OMT) (Rumbaugh 1991), Object Oriented Software
Engineering (Objectory) (Jacobson 1992), Object Oriented Analysis
(OOA)
(Shlaer and Mellor 1992), The Fusion Method (Coleman 1991).
10. 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.
11. 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. The following
code snippet shows this:
class Sample
{
public:
int *ptr;
Sample(int i)
{
ptr = new int(i);
}
~Sample()
{
delete ptr;
}
void PrintVal()
{
cout << "The value is " << *ptr;
}
};
void SomeFunc(Sample x)
{
cout << "Say i am in someFunc " << endl;
}
int main()
{
Sample s1 = 10;
SomeFunc(s1);
s1.PrintVal();
}
In the above example when PrintVal() function is
called it is called by the pointer that has been freed by the
destructor in SomeFunc.
12. Differentiate between the message and method.
Message:
a. Objects communicate by sending messages to each other.
b. A message is sent to invoke a method.
Method
c. Provides response to a message.
d. It is an implementation of an operation.
13. 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.
14. 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.
15. What is class invariant?
A class invariant is a condition that defines all valid states for an object. It is a logical condition to ensure the correct working of a class. Class invariants
must hold when an object is created, and they must be preserved under
all operations of the class. In particular all class invariants are
both preconditions and post-conditions for all operations or member
functions of the class.
16. What do you mean by Stack unwinding?
It is a process during exception handling when the destructor is called for all local objects between the place where the exception was thrown and
where it is caught.
17. Define precondition and post-condition to a member function.
Precondition: A precondition is a condition that must be true on entry
to a member function. A class is used correctly if preconditions are
never false. An operation is not responsible for doing anything
sensible if its precondition fails to hold. For example, the interface
invariants of stack class say nothing about pushing yet another
element
on a stack that is already full. We say that isful() is a precondition
of the push operation.
Post-condition: A post-condition is a condition
that must be true on exit from a member function if the precondition
was valid on entry to that function. A class is implemented correctly
if post-conditions are never false. For example, after pushing an
element on the stack, we know that isempty() must necessarily hold.
This is a post-condition of the push operation.
18. What are the conditions that have to be met for a condition to be
an invariant of the class?
a. The condition should hold at the end of every constructor.
b. The condition should hold at the end of every mutator (non-const)
operation.
19. What are proxy objects? Objects that stand for other objects are
called proxy objects or surrogates.
template
class Array2D
{
public:
class Array1D
{
public:
T& operator[] (int index);
const T& operator[] (int index)const;
};
Array1D operator[] (int index);
const Array1D operator[] (int index) const;
};
The following then becomes legal:
Array2D
cout<
Here data[3] yields an Array1D object
and the operator [] invocation on that object yields the float in
position(3,6) of the original two dimensional array. Clients of the
Array2D class need not be aware of the presence of the Array1D class.
Objects of this latter class stand for one-dimensional array objects
that, conceptually, do not exist for clients of Array2D. Such clients
program as if they were using real, live, two-dimensional arrays. Each
Array1D object stands for a one-dimensional array that is absent from
a
conceptual model used by the clients of Array2D. In the above example,
Array1D is a proxy class. Its instances stand for one-dimensional
arrays that, conceptually, do not exist.
20. Name some pure object oriented languages.
Smalltalk, Java, Eiffel, Sather.
21. Name the operators that cannot be overloaded.
sizeof, ., .*, .- >, ::, ?: Salam in the comments notes that -> can be overloaded.
22. What is a node class?
A node class is a class that, relies on the base class for services and implementation, provides a wider interface to the users than its base class,
relies primarily on virtual functions in its public interface depends on all its direct and indirect base class can be understood only in the context of the base class can be used as base for further derivation can be used to create objects.
A node class is a class that has added new services or functionality
beyond the services inherited from its base class.
23. What is an orthogonal base class?
If two base classes have no overlapping methods or data they are said
to be independent of, or orthogonal to each other. Orthogonal in the
sense means that two classes operate in different dimensions and do
not
interfere with each other in any way. The same derived class may
inherit such classes with no difficulty.
24. What is a container class? What are the types of container
classes?
A container class is a class that is used to hold objects in memory or
external storage. A container class acts as a generic holder. A
container class has a predefined behavior and a well-known interface.
A container class is a supporting class whose purpose is to hide the
topology used for maintaining the list of objects in memory. When a
container class contains a group of mixed objects, the container is
called a heterogeneous container; when the container is holding a
group
of objects that are all the same, the container is called a
homogeneous
container.
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