* DATA STRUCTURE APTITUDE *
1. What is data structure?
A data structure is a way of organizing data that
considers not only the items stored, but also their
relationship to each other. Advance knowledge about
the relationship between data items allows designing of
efficient algorithms for the manipulation of data.
2. List out the areas in which data
structures are
applied extensively?
Compiler Design,
Operating System,
Database Management System,
Statistical analysis package,
Numerical Analysis,
Graphics,
Artificial Intelligence,
Simulation
3. What are the major data structures
used in the
following areas : RDBMS, Network data
model &
Hierarchical data model.
RDBMS – Array (i.e. Array of
structures)
Network data model – Graph
Hierarchical data model – Trees
4. If you are using C language to
implement the
heterogeneous linked list, what pointer
type will you
use?
The heterogeneous linked list contains different
data types in its nodes and we need a link, pointer to
connect them. It is not possible to use ordinary pointers
for this. So we go for void pointer. Void pointer is
capable of storing pointer to any type as it is a generic
pointer type.
5. Minimum number of queues needed to
implement
the priority queue?
Two. One queue is used for actual storing of data
and another for storing priorities.
6. What is the data structures used to
perform
recursion?
Stack. Because of its LIFO (Last In First Out)
property it remembers its ‘caller’ so knows whom to
return when the function has to return. Recursion makes
use of system stack for storing the return addresses of
the function calls.
Every recursive function has its
equivalent
iterative (non-recursive) function. Even when such
equivalent iterative procedures are written, explicit
stack is to be used.
7. What are the notations used in
Evaluation of
Arithmetic Expressions using prefix and
postfix
forms?
Polish and Reverse Polish notations.
8. Convert the expression ((A + B) * C
– (D – E) ^
(F + G)) to equivalent Prefix and
Postfix notations.
Prefix Notation:
^ - * +ABC - DE + FG
Postfix Notation:
AB + C * DE - - FG + ^
9. Sorting is not possible by using
which of the
following methods?
(a) Insertion
(b) Selection
(c) Exchange
(d) Deletion
(d) Deletion.
Using insertion we can perform insertion sort,
using selection we can perform selection sort, using
exchange we can perform the bubble sort (and other
similar sorting methods). But no sorting method can be
done just using deletion.
10. A binary tree with 20 nodes has
null
branches?
21
Let us take a tree with 5 nodes (n=5)
It will have only 6 (ie,5+1) null branches. In general,
A binary tree with n nodes has exactly
n+1 null
nodes.
11. What are the methods available in
storing
sequential files?
Straight merging,
Natural merging,
Null Branches
Polyphase sort,
Distribution of Initial runs.
12. How many different trees are
possible with 10
nodes ?
1014
For example, consider a tree with 3 nodes(n=3),
it will have the maximum combination of 5 different
(ie, 23 - 3 = 5) trees.
i ii
iii iv v
In general:
If there are n nodes, there exist 2n-n different
trees.
13. List out few of the Application of
tree datastructure?
The manipulation of Arithmetic expression,
Symbol Table construction,
Syntax analysis.
14. List out few of the applications
that make use of
Multilinked Structures?
Sparse matrix,
Index generation.
15. In tree construction which is the
suitable efficient
data structure?
(a) Array (b) Linked list (c)
Stack (d) Queue (e) none
(b) Linked list
16. What is the type of the algorithm
used in solving
the 8 Queens problem?
Backtracking
17. In an AVL tree, at what condition
the balancing is
to be done?
If the ‘pivotal value’ (or the ‘Height factor’) is
greater than 1 or less than –1.
18. What is the bucket size, when the
overlapping and
collision occur at same time?
One. If there is only one entry possible in the
bucket, when the collision occurs, there is no way to
accommodate the colliding value. This results in the
overlapping of values.
19. Traverse the given tree using
Inorder, Preorder and
Postorder traversals.
A
B C
D E F G
H I J
Given tree:
Inorder : D H B E A F C I G J
Preorder: A B D H E C F G I J
Postorder: H D E B F I J G C A
20. There are 8, 15, 13, 14 nodes were
there in 4
different trees. Which of them could
have formed a
full binary tree?
15.
In general:
There are 2n-1 nodes in a full binary tree.
By the method of elimination:
Full binary trees contain odd number of
nodes. So there cannot be full binary trees with 8 or 14
nodes, so rejected. With 13 nodes you can form a
complete binary tree but not a full binary tree. So the
correct answer is 15.
Note:
Full and Complete binary trees are different. All
full binary trees are complete binary
trees but not vice
versa.
21. In the given binary tree, using
array you can store
the node 4 at which location?
1
2 3
4
5
At location 6
* RDBMS CONCEPTS *
1. What is database?
A database is a logically coherent collection of
data with some inherent meaning, representing some
aspect of real world and which is designed, built and
populated with data for a specific purpose.
2. What is DBMS?
It is a collection of programs that enables user to
create and maintain a database. In other words it is
general-purpose software that provides the users with
the processes of defining, constructing and
manipulating the database for various applications.
3. What is a Database system?
The database and DBMS software together is
called as Database system.
4. Advantages of DBMS?
Redundancy is controlled.
Unauthorised access is restricted.
Providing multiple user interfaces.
Enforcing integrity constraints.
Providing backup and recovery.
5. Disadvantage in File Processing
System?
Data redundancy & inconsistency.
Difficult in accessing data.
Data isolation.
Data integrity.
Concurrent access is not possible.
Security Problems.
6. Describe the three levels of data
abstraction?
The are three levels of abstraction:
Physical level: The lowest level of abstraction
describes how data are stored.
Logical level: The next higher level of
abstraction, describes what data are stored in
database and what relationship among those data.
View level: The
highest level of abstraction
describes only part of entire database.
7. Define the "integrity
rules"
There are two Integrity rules.
Entity Integrity: States that “Primary key
cannot have NULL value”
Referential Integrity: States that “Foreign
Key can be either a NULL value or should
be Primary Key value of other relation.
8. What is extension and intension?
Extension -
It is the number of tuples present in a table
at any instance. This is time dependent.
Intension -
It is a constant value that gives the name,
structure of table and the constraints laid on it.
9. What is System R? What are its two
major
subsystems?
System R was designed and developed over a
period of 1974-79 at IBM San Jose Research Center. It
is a prototype and its purpose was to demonstrate that it
is possible to build a Relational System that can be used
in a real life environment to solve real life problems,
with performance at least comparable to that of existing
system.
Its two subsystems are
Research Storage
System Relational Data System.
10. How is the data structure of System
R different
from the relational structure?
Unlike Relational systems in System R
Domains are not supported
Enforcement of candidate key uniqueness
is optional
Enforcement of entity integrity is
optional
Referential integrity is not enforced
11. What is Data Independence?
Data independence means that “the application
is independent of the storage structure and access
strategy of data”. In other words, The ability to modify
the schema definition in one level should not affect the
schema definition in the next higher level.
Two types of Data Independence:
Physical Data Independence:
Modification in physical level should not
affect the logical level.
Logical Data Independence: Modification
in logical level should affect the view level.
NOTE: Logical Data Independence is more
difficult
to achieve
12. What is a view? How it is related
to data
independence?
A view may be thought of as a virtual table, that
is, a table that does not really exist in its own right but
is instead derived from one or more underlying base
table. In other words, there is no stored file that direct
represents the view instead a definition of view is
stored in data dictionary.
Growth and restructuring of base tables is not
reflected in views. Thus the view can insulate users
from the effects of restructuring and growth in the
database. Hence accounts for logical data
independence.
13. What is Data Model?
A collection of conceptual tools for describing
data, data relationships data semantics and constraints.
14. What is E-R model?
This data model is based on real world that
consists of basic objects called entities and of
relationship among these objects. Entities are described
in a database by a set of attributes.
15. What is Object Oriented model?
This model is based on collection of objects. An
object contains values stored in instance variables with
in the object. An object also contains bodies of
code that operate on the object. These bodies of code
are called methods. Objects that contain same types of
values and the same methods are grouped together into
classes.
16. What is an Entity?
It is a 'thing' in the real world with an independent
existence.
17. What is an Entity type?
It is a collection (set) of entities that have same
attributes.
18. What is an Entity set?
It is a collection of all entities of particular entity
type in the database.
19. What is an Extension of entity
type?
The collections of entities of a particular entity
type are grouped together into an entity set.
20. What is Weak Entity set?
An entity set may not have sufficient attributes to
form a primary key, and its primary key compromises
of its partial key and primary key of its parent entity,
then it is said to be Weak Entity set.
21. What is an attribute?
It is a particular property, which describes the
entity.
22.
* RDBMS CONCEPTS *
1. What is database?
A database is a logically coherent collection of
data with some inherent meaning, representing some
aspect of real world and which is designed, built and
populated with data for a specific purpose.
2. What is DBMS?
It is a collection of programs that enables user to
create and maintain a database. In other words it is
general-purpose software that provides the users with
the processes of defining, constructing and
manipulating the database for various applications.
3. What is a Database system?
The database and DBMS software together is
called as Database system.
4. Advantages of DBMS?
Redundancy is controlled.
Unauthorised access is restricted.
Providing multiple user interfaces.
Enforcing integrity constraints.
Providing backup and recovery.
5. Disadvantage in File Processing
System?
Data redundancy & inconsistency.
Difficult in accessing data.
Data isolation.
Data integrity.
Concurrent access is not possible.
Security Problems.
6. Describe the three levels of data
abstraction?
The are three levels of abstraction:
Physical level: The lowest level of abstraction
describes how data are stored.
Logical level: The next higher level of
abstraction, describes what data are stored in
database and what relationship among those data.
View level: The
highest level of abstraction
describes only part of entire database.
7. Define the "integrity
rules"
There are two Integrity rules.
Entity Integrity: States that “Primary key
cannot have NULL value”
Referential Integrity: States that “Foreign
Key can be either a NULL value or should
be Primary Key value of other relation.
8. What is extension and intension?
Extension -
It is the number of tuples present in a table
at any instance. This is time dependent.
Intension -
It is a constant value that gives the name,
structure of table and the constraints laid on it.
9. What is System R? What are its two
major
subsystems?
System R was designed and developed over a
period of 1974-79 at IBM San Jose Research Center. It
is a prototype and its purpose was to demonstrate that it
is possible to build a Relational System that can be used
in a real life environment to solve real life problems,
with performance at least comparable to that of existing
system.
Its two subsystems are
Research Storage
System Relational Data System.
10. How is the data structure of System
R different
from the relational structure?
Unlike Relational systems in System R
Domains are not supported
Enforcement of candidate key uniqueness
is optional
Enforcement of entity integrity is
optional
Referential integrity is not enforced
11. What is Data Independence?
Data independence means that “the application
is independent of the storage structure and access
strategy of data”. In other words, The ability to modify
the schema definition in one level should not affect the
schema definition in the next higher level.
Two types of Data Independence:
Physical Data Independence:
Modification in physical level should not
affect the logical level.
Logical Data Independence: Modification
in logical level should affect the view level.
NOTE: Logical Data Independence is more
difficult
to achieve
12. What is a view? How it is related
to data
independence?
A view may be thought of as a virtual table, that
is, a table that does not really exist in its own right but
is instead derived from one or more underlying base
table. In other words, there is no stored file that direct
represents the view instead a definition of view is
stored in data dictionary.
Growth and restructuring of base tables is not
reflected in views. Thus the view can insulate users
from the effects of restructuring and growth in the
database. Hence accounts for logical data
independence.
13. What is Data Model?
A collection of conceptual tools for describing
data, data relationships data semantics and constraints.
14. What is E-R model?
This data model is based on real world that
consists of basic objects called entities and of
relationship among these objects. Entities are described
in a database by a set of attributes.
15. What is Object Oriented model?
This model is based on collection of objects. An
object contains values stored in instance variables with
in the object. An object also contains bodies of
code that operate on the object. These bodies of code
are called methods. Objects that contain same types of
values and the same methods are grouped together into
classes.
16. What is an Entity?
It is a 'thing' in the real world with an independent
existence.
17. What is an Entity type?
It is a collection (set) of entities that have same
attributes.
18. What is an Entity set?
It is a collection of all entities of particular entity
type in the database.
19. What is an Extension of entity
type?
The collections of entities of a particular entity
type are grouped together into an entity set.
20. What is Weak Entity set?
An entity set may not have sufficient attributes to
form a primary key, and its primary key compromises
of its partial key and primary key of its parent entity,
then it is said to be Weak Entity set.
21. What is an attribute?
It is a particular property, which describes the
entity.
22. What is a Relation Schema and a
Relation?
A relation Schema denoted by R(A1, A2, …, An)
is made up of the relation name R and the list of
attributes Ai that it contains. A relation is defined as a
set of tuples. Let r be the relation which contains set
tuples (t1, t2, t3, ..., tn). Each tuple is an ordered list of
n-values t=(v1,v2, ..., vn).
23. What is degree of a Relation?
It is the number of attribute of its relation schema.
24. What is Relationship?
It is an association among two or more entities.
25. What is Relationship set?
The collection (or set) of similar relationships.
26. What is Relationship type?
Relationship type defines a set of associations or a
relationship set among a given set of entity types.
27. What is degree of Relationship
type?
It is the number of entity type participating.
28. What is DDL (Data Definition
Language)?
A data base schema is specifies by a set of
definitions expressed by a special language called DDL.
29. What is VDL (View Definition
Language)?
It specifies user views and their mappings to the
conceptual schema.
30. What is SDL
(Storage Definition Language)?
This language is to specify the internal schema.
This language may specify the mapping between two
schemas.
28. What is Data Storage - Definition
Language?
The storage structures and access methods used
by database system are specified by a set of definition
in a special type of DDL called data storage-definition
language.
29. What is DML (Data Manipulation
Language)?
This language that enable user to access or
manipulate data as organized by appropriate data
model.
Procedural DML or Low level: DML requires a
user to specify what data are needed and how to get
those data.
Non-Procedural DML or High level: DML
requires a user to specify what data are needed
without specifying how to get those data.
33. What is DML Compiler?
It translates DML statements in a query language
into low-level instruction that the query evaluation
engine can understand.
34. What is Query evaluation engine?
It executes low-level instruction generated by
compiler.
35. What is DDL Interpreter?
It interprets DDL statements and record them in
tables containing metadata.
36. What is Record-at-a-time?
The Low level or Procedural DML can specify
and retrieve each record from a set of records. This
retrieve of a record is said to be Record-at-a-time.
37. What is Set-at-a-time or
Set-oriented?
The High level or Non-procedural DML can
specify and retrieve many records in a single DML
statement. This retrieve of a record is said to be Set-ata-
time or Set-oriented.
38. What is Relational Algebra?
It is procedural query language. It consists of a set
of operations that take one or two relations as input and
produce a new relation.
39. What is Relational Calculus?
It is an applied predicate calculus specifically
tailored for relational databases proposed by E.F. Codd.
E.g. of languages based on it are DSL ALPHA, QUEL.
40. How does Tuple-oriented relational
calculus differ
from domain-oriented relational
calculus
The tuple-oriented calculus uses a tuple variables
i.e., variable whose only permitted values are tuples of
that relation. E.g. QUEL
The domain-oriented calculus has domain variables i.e.,
variables that range over the underlying domains
instead of over relation. E.g. ILL, DEDUCE.
41. What is normalization?
It is a process of analysing the given relation
schemas based on their Functional Dependencies (FDs)
and primary key to achieve the properties
Minimizing redundancy
Minimizing insertion, deletion and update
anomalies.
42. What is Functional Dependency?
A Functional dependency is denoted by X -> Y
between two sets of attributes X and Y that are subsets
of R specifies a constraint on the possible tuple that can
form a relation state r of R. The constraint is for any
two tuples t1 and t2 in r if t1[X] = t2[X] then they have
t1[Y] = t2[Y]. This means the value of X component of
a tuple uniquely determines the value of component Y.
43. When is a functional dependency F
said to be
minimal?
Every dependency in F has a single attribute for
its right hand side.
We cannot replace any dependency X -> A in F
with a dependency Y-> A where Y is a proper
subset of X and still have a set of dependency that is
equivalent to F.
We cannot remove any dependency from F and
still have set of dependency that is equivalent to F.
44. What is Multivalued dependency?
Multivalued dependency denoted by X -> Y
specified on relation schema R, where X and Y are both
subsets of R, specifies the following constraint on any
relation r of R: if two tuples t1 and t2 exist in r such that
t1[X] = t2[X] then t3 and t4 should also exist in r with
the following properties
t3[x] = t4[X] = t1[X] = t2[X]
t3[Y] = t1[Y] and t4[Y] = t2[Y]
t3[Z] = t2[Z] and t4[Z] = t1[Z]
where [Z = (R-(X U Y)) ]
45. What is Lossless join property?
It guarantees that the spurious tuple generation
does not occur with respect to relation schemas after
decomposition.
46. What is 1 NF (Normal Form)?
The domain of attribute must include only atomic
(simple, indivisible) values.
47. What is Fully Functional
dependency?
It is based on concept of full functional
dependency. A functional dependency X-> Y is full
functional dependency if removal of any attribute A
from X means that the dependency does not hold any
more.
48. What is 2NF?
A relation schema R is in 2NF if it is in 1NF and
every non-prime attribute A in R is fully functionally
dependent on primary key.
49. What is 3NF?
A relation schema R is in 3NF if it is in 2NF and
for every FD X-> A either of the following is true
X is a Super-key of R.
A is a prime attribute of R.
In other words, if every non prime attribute is
non-transitively dependent on primary key.
50. What is BCNF (Boyce-Codd Normal
Form)?
A relation schema R is in BCNF if it is in 3NF and
satisfies additional constraints that for every FD X ->
A, X must be a candidate key.
51. What is 4NF?
A relation schema R is said to be in 4NF if for
every Multivalued dependency X -> Y that holds
over R, one of following is true
X is subset or equal to (or) XY = R.
X is a super key.
52. What is 5NF?
A Relation schema R is said to be 5NF if for every
join dependency {R1, R2, ..., Rn} that holds R, one the
following is true
Ri = R for some i.
The join dependency is implied by the set of FD,
over R in which the left side is key of R.
53. What is Domain-Key Normal Form?
A relation is said to be in DKNF if all constraints
and dependencies that should hold on the the
constraint can be enforced by simply enforcing
the domain constraint and key constraint on the
relation.
54. What are partial, alternate,,
artificial, compound
and natural key?
Partial Key:
It is a set of attributes that can uniquely
identify weak entities and that are related to same
owner entity. It is sometime called as Discriminator.
Alternate Key:
All Candidate Keys excluding the Primary
Key are known as Alternate Keys.
Artificial Key:
If no obvious key, either stand alone or
compound is available, then the last resort is to simply
create a key, by assigning a unique number to each
record or occurrence. Then this is known as developing
an artificial key.
Compound Key:
If no single data element uniquely
identifies occurrences within a construct, then
combining multiple elements to create a unique
identifier for the construct is known as creating a
compound key.
Natural Key:
When one of the data elements stored
within a construct is utilized as the primary key, then it
is called the natural key.
56. What is indexing and what are the
different kinds of
indexing?
Indexing is a technique for determining how
quickly specific data can be found.
Types:
Binary search style indexing
B-Tree indexing
Inverted list indexing
Memory resident table
Table indexing
57. What is system catalog or catalog
relation? How is
better known as?
A RDBMS maintains a description of all the data
that it contains, information about every relation and
index that it contains. This information is stored in a
collection of relations maintained by the system called
metadata. It is also called data dictionary.
58. What is meant by query
optimization?
The phase that identifies an efficient execution
plan for evaluating a query that has the least estimated
cost is referred to as query optimization.
59. What is join dependency and
inclusion
dependency?
Join Dependency:
A Join dependency is
generalization of Multivalued dependency.A JD {R1,
R2, ..., Rn} is said to hold over a relation R if R1, R2,
R3, ..., Rn is a lossless-join decomposition of R . There
is no set of sound and complete inference rules for JD.
Inclusion Dependency:
An Inclusion Dependency is a statement
of the form that some columns of a relation are
contained in other columns. A foreign key constraint is
an example of inclusion dependency.
60. What is durability in DBMS?
Once the DBMS informs the user that a
transaction has successfully completed, its effects
should persist even if the system crashes before all its
changes are reflected on disk. This property is called
durability.
61. What do you mean by atomicity and
aggregation?
Atomicity:
Either all actions are carried out or none are.
Users should not have to worry about the effect of
incomplete transactions. DBMS ensures this by
undoing the actions of incomplete transactions.
Aggregation:
A concept which is used to model a
relationship between a collection of entities and
relationships. It is used when we need to express a
relationship among relationships.
62. What is a Phantom Deadlock?
In distributed deadlock detection, the delay in
propagating local information might cause the deadlock
detection algorithms to identify deadlocks that do not
really exist. Such situations are called phantom
deadlocks and they lead to unnecessary aborts.
63. What is a checkpoint and when does
it occur?
A Checkpoint is like a snapshot of the DBMS
state. By taking checkpoints, the DBMS can reduce the
amount of work to be done during restart in the event of
subsequent crashes.
64. What are the different phases of
transaction?
Different phases are
Analysis phase
Redo Phase
Undo phase
65. What do you mean by flat file
database?
It is a database in which there are no programs or
user access languages. It has no cross-file capabilities
but is user-friendly and provides user-interface
management.
66. What is "transparent
DBMS"?
It is one, which keeps its Physical Structure
hidden from user.
67. Brief theory of Network,
Hierarchical schemas and
their properties
Network schema uses a graph data structure to
organize records example for such a database
management system is CTCG while a hierarchical
schema uses a tree data structure example for such a
system is IMS.
68. What is a query?
A query with respect to DBMS relates to user
commands that are used to interact with a data base.
The query language can be classified into data
definition language and data manipulation language.
69. What do you mean by Correlated
subquery?
Subqueries, or nested queries, are used to bring
back a set of rows to be used by the parent query.
Depending on how the subquery is written, it can be
executed once for the parent query or it can be executed
once for each row returned by the parent query. If the
subquery is executed for each row of the parent, this is
called a correlated subquery.
A correlated subquery can be easily identified if it
contains any references to the parent subquery columns
in its WHERE clause. Columns from the subquery
cannot be referenced anywhere else in the parent query.
The following example demonstrates a non-correlated
subquery.
E.g. Select * From CUST Where '10/03/1990' IN
(Select ODATE From ORDER Where CUST.CNUM =
ORDER.CNUM)
70.What are the primitive operations
common to all
record management systems?
Addition, deletion and modification.
71. Name the buffer in which all the
commands that are
typed in are stored
‘Edit’ Buffer
72. What are the unary operations in
Relational
Algebra?
PROJECTION and SELECTION.
73. Are the resulting
relations of PRODUCT and JOIN
operation the same?
No.
PRODUCT: Concatenation of every row in one
relation with every row in another.
JOIN: Concatenation of rows from one relation
and related rows from another.
74. What is RDBMS KERNEL?
Two important pieces of RDBMS architecture
are the kernel, which is the software, and the data
dictionary, which consists of the system-level data
structures used by the kernel to manage the database
You might think of an RDBMS as an operating
system (or set of subsystems), designed specifically for
controlling data access; its primary functions are
storing, retrieving, and securing data. An RDBMS
maintains its own list of authorized users and their
associated privileges; manages memory caches and
paging; controls locking for concurrent resource usage;
dispatches and schedules user requests; and manages
space usage within its table-space structures
.
75. Name the sub-systems of a RDBMS
I/O, Security, Language Processing, Process
Control, Storage Management, Logging and Recovery,
Distribution Control, Transaction Control, Memory
Management, Lock Management
76. Which part of the RDBMS takes care
of the data
dictionary? How
Data dictionary is a set of tables and database
objects that is stored in a special area of the database
and maintained exclusively by the kernel.
77. What is the job of the information
stored in datadictionary?
The information in the data dictionary validates
the existence of the objects, provides access to them,
and maps the actual physical storage location.
78. Not only RDBMS takes care of
locating data it also
determines an optimal access path to store or
retrieve the data
79. How do you communicate with an
RDBMS?
You communicate with an RDBMS using
Structured Query Language (SQL)
80. Define SQL and
state the differences between SQL
and other conventional programming
Languages
SQL is a nonprocedural language that is designed
specifically for data access operations on normalized
relational database structures. The primary difference
between SQL and other conventional programming
languages is that SQL statements specify what data
operations should be performed rather than how to
perform them.
81. Name the three major set of files
on disk that
compose a database in Oracle
There are three major sets of files on disk that
compose a database. All the files are binary. These are
Database files
Control files
Redo logs
The most important of these are the database files
where the actual data resides. The control files and the
redo logs support the functioning of the architecture
itself.
All three sets of files must be present, open, and
available to Oracle for any data on the database to be
useable. Without these files, you cannot access the
database, and the database administrator might have to
recover some or all of the database using a backup, if
there is one.
82. What is an Oracle Instance?
The Oracle system processes, also known as
Oracle background processes, provide functions for the
user processes—functions that would otherwise be done
by the user processes themselves
Oracle database-wide system memory is known as
the SGA, the system global area or shared global area.
The data and control structures in the SGA are
shareable, and all the Oracle background processes and
user processes can use them.
The combination of the SGA and the Oracle
background processes is known as an Oracle instance
83. What are the four Oracle system
processes that
must always be up and running for the
database to be
useable
The four Oracle system processes that must
always be up and running for the database to be useable
include DBWR (Database Writer), LGWR (Log Writer),
SMON (System Monitor), and PMON (Process
Monitor).
84. What are database files, control
files and log files.
How many of these files should a
database have at
least? Why?
Database Files
The database files hold the actual data and
are typically the largest in size. Depending on their
sizes, the tables (and other objects) for all the user
accounts can go in one database file—but that's not an
ideal situation because it does not make the database
structure very flexible for controlling access to storage
for different users, putting the database on different disk
drives, or backing up and restoring just part of the
database.
You must have at least one database file but
usually, more than one files are used. In terms of
accessing and using the data in the tables and other
objects, the number (or location) of the files is
immaterial.
The database files are fixed in size and never
grow bigger than the size at which they were created
Control Files
The control files and redo logs support the
rest of the architecture. Any database must have at least
one control file, although you typically have more than
one to guard against loss. The control file records the
name of the database, the date and time it was created,
the location of the database and redo logs, and the
synchronization information to ensure that all three sets
of files are always in step. Every time you add a new
database or redo log file to the database, the
information is recorded in the control files.
Redo Logs
Any database must have at least two redo
logs. These are the journals for the database; the redo
logs record all changes to the user objects or system
objects. If any type of failure occurs, the changes
recorded in the redo logs can be used to bring the
database to a consistent state without losing any
committed transactions. In the case of non-data loss
failure, Oracle can apply the information in the redo
logs automatically without intervention from the DBA.
The redo log files are fixed in size and never
grow dynamically from the size at which they were
created.
85. What is ROWID?
The ROWID is a unique database-wide physical
address for every row on every table. Once assigned
(when the row is first inserted into the database), it
never changes until the row is deleted or the table is
dropped.
The ROWID consists of the following three
components, the combination of which uniquely
identifies the physical storage location of the row.
Oracle database file number, which contains
the block with the rows
Oracle block address, which contains the
row
The row within the block (because each
block can hold many rows)
The ROWID is used internally in indexes as a
quick means of retrieving rows with a particular key
value. Application developers also use it in SQL
statements as a quick way to access a row once they
know the ROWID
86. What is Oracle Block? Can two
Oracle Blocks have
the same address?
Oracle "formats" the database files into a
number of Oracle blocks when they are first created—
making it easier for the RDBMS software to manage
the files and easier to read data into the memory areas.
The block size should be a multiple of the
operating system block size. Regardless of the block
size, the entire block is not available for holding data;
Oracle takes up some space to manage the contents of
the block. This block header has a minimum size, but it
can grow.
These Oracle blocks are the smallest unit of
storage. Increasing the Oracle block size can improve
performance, but it should be done only when the
database is first created.
Each Oracle block is numbered sequentially for
each database file starting at 1. Two blocks can have the
same block address if they are in different database
files.
87. What is database Trigger?
A database trigger is a PL/SQL block that can
defined to automatically execute for insert, update, and
delete statements against a table. The trigger can e
defined to execute once for the entire statement or once
for every row that is inserted, updated, or deleted. For
any one table, there are twelve events for which you
can define database triggers. A database trigger can call
database procedures that are also written in PL/SQL.
88. Name two utilities that Oracle
provides, which are
use for backup and recovery.
Along with the RDBMS software, Oracle
provides two utilities that you can use to back up and
restore the database. These utilities are Export and
Import.
The Export utility dumps the definitions and data
for the specified part of the database to an operating
system binary file. The Import utility reads the file
produced by an export, recreates the definitions of
objects, and inserts the data
If Export and Import are used as a means of
backing up and recovering the database, all the changes
made to the database cannot be recovered since the
export was performed. The best you can do is recover
the database to the time when the export was last
performed.
89. What are stored-procedures? And
what are the
advantages of using them.
Stored procedures are database objects that
perform a user defined operation. A stored procedure
can have a set of compound SQL statements. A stored
procedure executes the SQL commands and returns the
result to the client. Stored procedures are used to reduce
network traffic.
90. How are exceptions handled in
PL/SQL? Give some
of the internal exceptions' name
PL/SQL exception handling is a mechanism for
dealing with run-time errors encountered during
procedure execution. Use of this mechanism enables
execution to continue if the error is not severe enough
to cause procedure termination.
The exception handler must be defined within a
subprogram specification. Errors cause the program to
raise an exception with a transfer of control to the
exception-handler block. After the exception handler
executes, control returns to the block in which the
handler was defined. If there are no more executable
statements in the block, control returns to the caller.
User-Defined Exceptions
PL/SQL enables the user to define exception
handlers in the declarations area of subprogram
specifications. User accomplishes this by naming an
exception as in the following example:
ot_failure EXCEPTION;
In this case, the exception name is ot_failure. Code
associated with this handler is written in the
EXCEPTION specification area as follows:
EXCEPTION
when OT_FAILURE then
out_status_code :=
g_out_status_code;
out_msg := g_out_msg;
The following is an example of a subprogram
exception:
EXCEPTION
when NO_DATA_FOUND then
g_out_status_code := 'FAIL';
RAISE ot_failure;
Within this exception is the RAISE statement that
transfers control back to the ot_failure exception
handler. This technique of raising the exception is used
to invoke all user-defined exceptions.
System-Defined Exceptions
Exceptions internal to PL/SQL are raised
automatically upon error. NO_DATA_FOUND is a
system-defined exception. Table below gives a
complete list of internal exceptions.
PL/SQL internal exceptions.
Exception Name Oracle Error
CURSOR_ALREADY_OPEN ORA-06511
DUP_VAL_ON_INDEX ORA-00001
INVALID_CURSOR ORA-01001
INVALID_NUMBER ORA-01722
LOGIN_DENIED ORA-01017
NO_DATA_FOUND ORA-01403
NOT_LOGGED_ON ORA-01012
PROGRAM_ERROR ORA-06501
STORAGE_ERROR ORA-06500
TIMEOUT_ON_RESOURCE ORA-00051
TOO_MANY_ROWS ORA-01422
TRANSACTION_BACKED_OUTORA-00061
VALUE_ERROR ORA-06502
ZERO_DIVIDE ORA-01476
In addition to this list of exceptions, there is a
catch-all exception named OTHERS that traps all errors
for which specific error handling has not been
established.
91. Does PL/SQL support
"overloading"? Explain
The concept of overloading in PL/SQL
relates
to the idea that you can define procedures and functions
with the same name. PL/SQL does not look only at the
referenced name, however, to resolve a procedure or
function call. The count and data types of formal
parameters are also considered.
PL/SQL also attempts to resolve any procedure or
function calls in locally defined packages before
looking at globally defined packages or internal
functions. To further ensure calling the proper
procedure, you can use the dot notation. Prefacing a
procedure or function name with the package name
fully qualifies any procedure or function reference.
92. Tables derived from the ERD
a) Are totally unnormalised
b) Are always in 1NF
c) Can be further denormalised
d) May have multi-valued attributes
(b) Are always in 1NF
93. Spurious tuples may occur due to
i. Bad normalization
ii. Theta joins
iii. Updating tables from join
a) i & ii b) ii & iii
c) i & iii d) ii & iii
(a) i & iii because theta joins are joins made on
keys that are not primary keys.
94. A B C is a set of attributes. The
functional
dependency is as follows
AB -> B
AC -> C
C -> B
a) is in 1NF
b) is in 2NF
c) is in 3NF
d) is in BCNF
(a) is in 1NF since (AC)+ = { A, B, C} hence AC
is the primary key. Since C B is a FD given,
where neither C is a Key nor B is a prime attribute, this
it is not in 3NF. Further B is not functionally dependent
on key AC thus it is not in 2NF. Thus the given FDs is
in 1NF.
95. In mapping of ERD to DFD
a) entities in ERD should correspond to an
existing entity/store in DFD
b) entity in DFD is converted to attributes of an
entity in ERD
c) relations in ERD has 1 to 1 correspondence to
processes in DFD
d) relationships in ERD has 1 to 1
correspondence to flows in DFD
(a) entities in ERD should correspond to an
existing entity/store in DFD
96. A dominant entity is the entity
a) on the N side in a 1 : N relationship
b) on the 1 side in a 1 : N relationship
c) on either side in a 1 : 1 relationship
d) nothing to do with 1 : 1 or 1 : N relationship
(b) on the 1 side in a 1 : N relationship
97. Select 'NORTH', CUSTOMER From
CUST_DTLS
Where REGION = 'N' Order By CUSTOMER
Union
Select 'EAST', CUSTOMER From CUST_DTLS
Where
REGION = 'E' Order By CUSTOMER
The above is
a) Not an error
b) Error - the string in single quotes 'NORTH'
and 'SOUTH'
c) Error - the string should be in double quotes
d) Error - ORDER BY clause
(d) Error - the ORDER BY clause. Since ORDER
BY clause cannot be used in UNIONS
98. What is Storage Manager?
It is a program module that provides the interface
between the low-level data stored in database,
application programs and queries submitted to the
system.
99. What is Buffer Manager?
It is a program module, which is responsible for
fetching data from disk storage into main memory and
deciding what data to be cache in memory.
100. What is Transaction Manager?
It is a program module, which ensures that
database, remains in a consistent state despite system
failures and concurrent transaction execution proceeds
without conflicting.
101. What is File Manager?
It is a program module, which manages the
allocation of space on disk storage and data structure
used to represent information stored on a disk.
102. What is Authorization and
Integrity manager?
It is the program module, which tests for the
satisfaction of integrity constraint and checks the
authority of user to access data.
103. What are stand-alone procedures?
Procedures that are not part of a package are
known as stand-alone because they independently
defined. A good example of a stand-alone procedure is
one written in a SQL*Forms application. These types of
procedures are not available for reference from other
Oracle tools. Another limitation of stand-alone
procedures is that they are compiled at run time, which
slows execution.
104. What are cursors give different
types of cursors.
PL/SQL uses cursors for all database
information accesses statements. The language supports
the use two types of cursors
Implicit
Explicit
105. What is cold backup and hot backup
(in case of
Oracle)?
Cold Backup:
It is copying the three sets of files
(database files, redo logs, and control file) when the
instance is shut down. This is a straight file copy,
usually from the disk directly to tape. You must shut
down the instance to guarantee a consistent copy.
If a cold backup is performed, the only
option available in the event of data file loss is restoring
all the files from the latest backup. All work performed
on the database since the last backup is lost.
Hot Backup:
Some sites (such as worldwide airline
reservations systems) cannot shut down the database
while making a backup copy of the files. The cold
backup is not an available option.
So different means of backing up
database must be used — the hot backup. Issue a SQL
command to indicate to Oracle, on a tablespace-bytablespace
basis, that the files of the tablespace are to
backed up. The users can continue to make full use of
the files, including making changes to the data. Once
the user has indicated that he/she wants to back up the
tablespace files, he/she can use the operating system to
copy those files to the desired backup destination.
The database must be running in
ARCHIVELOG mode for the hot backup option.
If a data loss failure does occur, the lost
database files can be restored using the hot backup and
the online and offline redo logs created since the
backup was done. The database is restored to the most
consistent state without any loss of committed
transactions.
106. What are Armstrong rules? How do
we say that
they are complete and/or sound?
The well-known inference rules for FDs
Reflexive rule :
If Y is subset or equal to X then
X -> Y.
Augmentation rule:
If X -> Y then XZ -> YZ.
Transitive rule:
If {X->Y, Y -> Z} then X -> Z.
Decomposition rule :
If X -> YZ then X-> Y.
Union or Additive rule:
If {X -> Y, X -> Z} then X ->
Y Z.
Pseudo Transitive rule :
If {X -> Y, WY -> Z} then
WX -> Z.
Of these the first three are known as Amstrong
Rules. They are sound because it is enough if a set of
FDs satisfy these three. They are called complete
because using these three rules we can generate the rest
all inference rules.
107. How can you find the minimal key
of relational
schema?
Minimal key is one which can identify each tuple
of the given relation schema uniquely. For finding the
minimal key it is required to find the closure that is the
set of all attributes that are dependent on any given set
of attributes under the given set of functional
dependency.
Algo. I Determining X+, closure for X, given set
of FDs F
1. Set X+ = X
2. Set Old X+ = X+
3. For each FD Y -> Z in F and if
Y belongs to X+ then add Z to X+
4. Repeat steps 2 and 3 until Old X+
= X+
Algo.II Determining minimal K for relation
schema R, given set of FDs F
1. Set K to R that is make K a set of
all attributes in R
2. For each attribute A in K
a. Compute (K – A)+ with
respect to F
b. If (K – A)+ = R then set K =
(K – A)+
108. What do you understand by
dependency
preservation?
Given a relation R and a set of FDs F,
dependency preservation states that the closure of the
union of the projection of F on each decomposed
relation Ri is equal to the closure of F. i.e.,
((PR1(F)) U … U (PRn(F)))+ = F+
if decomposition is not dependency preserving, then
some dependency is lost in the decomposition.
109. What is meant by Proactive,
Retroactive and
Simultaneous Update.
Proactive Update:
The updates that are applied to
database before it becomes effective in real world.
Retroactive Update:
The updates that are applied to
database after it becomes effective in real world.
Simultaneous Update:
The updates that are applied to
database at the same time when it becomes effective in
real world.
110. What are the different types of
JOIN operations?
Equi Join: This is the most common type of join which
involves only equality comparisons. The disadvantage
in this type of join is that there.
more.......
1.#include
<stdio.h>
void
main()
{
int x = 5;
printf("%d,%d,%d",x,(x<<2),(x>>2));
}
Ans:
5,20,1
2.#include
<stdio.h>
void
main()
{
char
a[]="hello";
char
b[]="hai";
a=b;
printf("%s,%s",a,b);
}
ANs :
since a is the base address of the array it is
a
lValue(constant)
which can
not be assigned with a value a=b is a
error.
3.#include
<stdio.h>
void
main()
{
char * p =
"hello",ch;
ch = *++p;
printf("%c,%s",ch,p);
}
Ans e,ello
4.#include
<stdio.h>
#include
<string.h>
#define
TOTAL 3
#define
MAXNAMELEN 80
struct
company
{
char
organization[TOTAL][MAXNAMELEN];
};
int main()
{
void
nameswap(struct company)
struct
company x;
int i;
strcpy(x.organisation[0],"AATT
India");
strcpy(x.organisation[1],"AATT
Corporation");
strcpy(x.organisation[2],"AATT
Limited");
nameswap(x);
for(i=0;i<TOTAL;i++)
printf("\n
%s",x.organisation[i]);
return(1);
}
void
nameswap(struct company x)
{
char
tempname[MAXNAMELEN];
strcpy(tempname,x.organisation[0]);
strcpy(x.organisation[0],x.organisation[1]);
strcpy(x.organisation[1],tempname);
return;
}
Ans : AATT
India
AATT
Corporation
AATT
Limited
5 #inlcude
<stdio.h>
#define
Stringizer(x) printf(#x)
void
main()
{
Stringizer(hello);
}
Ans: '#'
is called Stringizer Operator - #x converts
x to
String Constant
6.
#include <stdio.h>
#define
Charizing(x) printf("%d",#@x)
void
main()
{
Charizing(a);
}
Ans : 97
7.#include<stdio.h>
#include<string.h>
int main(
)
{
char
*ptr1,*ptr2;
ptr1 =
"Hello AATT";
ptr2 =
"Hai";
ptr1=
strcat(ptr1,ptr2);
printf("\n
Input string %s",ptr1);
return 1;
}
Ans :
Enough memory not allocated for
concatenation
8.int
main( )
{
int
x=20,y=35;
x=y++ +
x++;
y=++y +
++x;
printf("%d
%d",x,y);
return 1;
}
Ans :
57,94
9.int
main( )
{
int i,*p;
i=10;
p=&i;
printf("%d",10/*p);
return 1;
}
Ans:Since
there is no space between / and * it is
taken to
be a comment and the output will not be
10/10 =1
as expected
10.
#include <stdio.h>
int main()
{
int a=0;
if(a= 0)
printf("hello");
printf("AATT");
return 0;
}
Ans :AATT
11.Write a
function to swap two numbers without
using temp
.
Ans :
Swap(a,b)
{
a= a+b;
b= a-b;
a= a-b;
}
12.O/p of
Following
int main()
{
char a[2];
*a[0]=7;
*a[1]=5;
printf("%d",&a[1]-a);
}
Ans
illegal indirection
13.
int main()
{
char
a[]="hellow";
char
*b="hellow";
char
c[5]="hellow";
printf("%s
%s %s ",a,b,c);
printf("
%d,%d,%d",sizeof(a),sizeof(b),sizeof(c));
}
ans :
7,4,5 (Size of b is dependent on the
machine)
14.
#define min(a,b) ((a)<(b))?(a):(b)
main()
{
int
i=0,a[20],*ptr;
ptr=a;
while(min(ptr++,&a[9])<&a[8])
i=i+1;
printf("i=%d\n",i);
}
Ans :5
15.Prog to
find PrimeFactors
void
Prime( int);
int main()
{
Prime(56);
}
void Prime
(int a)
{
int j;
for(j=1;
j<=a; j++)
{
if(a% j ==
0)
{
a/=j;
printf("%d,",j);
j= 1;
}}
return ;
}
16
Function to Reverse the string .
char *
reverse(char a[])
{
int len
,i=0;
char * p;
len =
strlen(a);
p =(char
*) malloc(len+1);
while(i<=
len)
{
p[i++] =
a[len -i];
}
p[len] =
'\0';
return p;
}
17. Output
of
int main()
{
printf("%d%x\n",0x2,12);
}
ans :2C
18.swap
two var without Temp and Arithmetic ops
Ans:
swap(a,b)
{
a=a^b;
b=a^b;
a=a^b;
}
19.int
main()
{
int
a[5],*p;
for(p=a;p<&a[5];p++)
{
*p=p-a;
printf("%d\n",*p);
}
}
Ans :
0,1,2,3,4
20.Prg to
Reverse A number
Reverse(n)
{
int result
= 0;
while(n!=0)
{ temp = n
% 10;
result
=result * 10 + temp
n = n/10;
}
return
result;
}
21. int
zap(int n)
{
if(n<=1)then
zap=1;
else
zap=zap(n-3)+zap(n-1);
}
then the
call zap(6) gives the values of zap
[a] 8 [b]
9 [c] 6 [d] 12 [e] 15
Ans b
22.op for
following prg
int main()
{
char
*x="new";
char
*y="dictonary";
void swap
(char * , char *);
swap
(x,y);
printf("(%s,
%s)",x,y);
}
void swap
(char *x,char *y)
{
char *t;
t=x;
x=y;
y=t;
printf("(%s,
%s)-",x,y);
}
a).(New,Dictionary)-(New,Dictionary)
b).(Dictionary,New)-(New,Dictionary)
c).(New,Dictionary)-(Dictionary,New)
d).(Dictionary,New)-(Dictionary,New)
e).None of
the above
Ans :c
23.
main()
{
main();
printf("InMain
\t");
}
Ans : No
Statement will be printed on the screen.
24.
main()
{
printf("InMain
\t");
main();
}
Ans ???
25.void
strcp1(char *s,char *t)
{
while(*t)
*s++ =
*t++;
}
main()
{
char a[] =
"God is great";
char b[] =
"god is man or god";
strcp1(b,a);
printf("%s",b);
}
Ans :GOD
IS GREAT man or god
26.int x ;
int intg()
{
return
x+=4;
}
int diff()
{
return
x/=4;
}
main()
{
x =
intg()+diff();
printf("%d",x);
}
Ans 5
27.
int x;
main()
{
int j =2;
printf("%d",fun(j));
}
fun(int x)
{
x++,++x;
return
x++;
}
Ans 4
28.
main()
{
static
char *s[] =
{"ice","green","cone","please"};
static
char **ptr[] = {s+3,s+2,s+1,s};
char ***p
= ptr;
printf("%s",**++p);
printf("\n%s",*--*++p
+3);
printf("\n%s",*p[-2]
+3);
printf("\n%s"
, p[-1][-1] +1);
}
Ans :
cone
ase
reen
29.
main()
{
float **a;
int i,j;
for(i=0;i<3;i++)
for(j=0;j<3;j++)
scanf("%f",&a[i][j]);
for(i=0;i<3;i++)
for(j=0;j<3;j++)
printf("%f",a[i][j]);
}
Ans :
Memory not
allocated for a
30.
main()
{
printf("%d",sizeof("1234"));
printf("%d",sizeof(1));
printf("%d",sizeof(1.1));
}
Ans 548
31.
main()
{
int *x;
int y[3] =
{10,20,30};
x=y;
printf("%d",++*x);
printf("\n%d",++*x++);
}
Ans 11,12
32.
int main()
{
char s[] =
"Get organised";
printf("%s",&s[2]);
printf("\n
%s",s);
printf("\n
%s",&s);
printf("\n
%c",s[2]);
}
Ans:
t
organised
Get
organised
Get
organised
t
33.
What is
the diff between the
i) int
const *k;
ii) int *
const k;
Ans : i)
specifies that k is a pointer to integer
constant ,
the k can be changed to point to
another
int value,but the value pointed by k can
not be
changed.
ii)
specifies that k is a constant pointer to an
integer ,
the value pointed to by the k can be
changed
,but the k can not be made to point to
another
integer .
34 .
main()
{
int const
*f;
int x =
10;
f = &
x;
*f = 15
printf("%d",x);
}
Ans :
f cannot
change the value of the pointed memory.
35.
main()
{
int const
*f;
int x =
10,y =15;
f = &
x;
printf("%d",*f);
f = &
y;
printf("%d",*f);
}
Ans :
f cannot
be assigned different addresses because
it is a
constant pointer.
36.
main()
{
int
a[6]={0,1,2,3,4,5};
int
(*p)[3];
p=a;
*p[1] = 5;
printf("%d",a[1]);
}
37.
main()
{
char i ;
for(i=0;i<256;i++)
printf("%d",i);
}
Ans
:Infinite loop
38.
main()
{
char
s[]="Hello World";
s++;
printf("%s",s);
}
Ans :S is
an l value ,cannot be a target of an
assignment
stmt.
39.main()
{
char
*s="Hello World";
s++;
printf("%s",s);
}
Ans : ello
world
40.
main()
{
char *s;
s =
"Hello World";
printf("%s",s);
}
Ans :Hello
World
41.
main()
{
int *s;
s =
"Hello World";
printf("%s",s);
}
Ans :Hello
World
42.
main()
{
char s[] =
"Hello";
printf("%s"
, s[3]);
}
Ans : %s
needs an address whereas s[3] returns a
content in
the location s+3.
43.
main()
{
extern int
a;
printf("%d",a);
}
Ans :
Linkage error .
44.
main()
{
inti=-3,j=2,k=0,m;
m=++i&&++j||++k;
printf("\n
%d %d %d %d",i,j,k,m);
}
Ans : 2 3
0 1
45.
main()
{
int a,b;
a=sumdig(123);
b=sumdig(123);
printf("%d
%d",a,b);
}
sumdig(int
n)
{
static int
s=0;
int d;
if(n!=0)
{
d=n%10;
n=(n-d)/10;
s=s+d;
sumdig(n);
}
else
return(s);
}
Ans :6,12
46.
#define CUBE(x)
(x*x*x)
main()
{
int a,b=3;
a=CUBE(b++);
printf("\n
%d %d",a,b);
}
Ans :27,6
47.
main()
{
char
*p,*f();
p=f();
printf("f()
returns:%s\n",p);
}
char *f()
{
char
result[80];
strcpy(result,"anything
will do");
return
(result);
}
Ans : f()
returns :
48.
main()
{
short int
*p,*q;
p=(short
int *)1000;
q=(short
int *)2000;
printf("%d",(q-p));
}
Ans 1000/2
= 500
49
main()
{
char a
=0xAA ;
int b ;
b = (int)
a ;
b = b
>> 4 ;
printf("%x",b);
}
Ans :
ffffffaa
50.
.main()
{
char *p =
"hello world!";
p[0] =
'H';
printf("%s",p);
}
Ans : Run
time error .
51.
main()
{
char *p ;
char s[20]
= "Hello world!";
strcpy(p,s);
printf("%s",p);
}
Ans : Run
time error
52.
main()
{
char *p ;
char s[20]
= "Hello world!";
p = (char
*)malloc(20);
strcpy(p,s);
printf("%s",p);
}
Ans :
Hello World!
53.
main()
{
int
a=10,b;
a>= 5 ?
b=100 : b=200;
printf("\n%d",b);
}
Ans
:lvalue required
54.
main()
{
int
a=10,b;
a>5 ?
a++ : a++;
printf("\n%d",a);
}
Ans : 11
55.
Given a
piece of code
int x[10];
int *ab;
ab=x;
To access
the 6th element of the array which of
the
following is incorrect?
(A) *(x+5)
(B) x[5] (C) ab[5] (D) *(*ab+5} .
Ans : d
56.
Consider
the following program
main()
{
int
a[5]={1,3,6,7,0};
int *b;
b=&a[2];
}
The value
of b[-1] is
(A) 1 (B)
3 (C) -6 (D) none
Ans : b
57.
What does
the following program print?
#include
<stio.h>
int
sum,count;
void
main(void)
{
for(count=5;sum+=--count;)
printf("%d",sum);
}
a. The pgm
goes to an infinite loop b. Prints
4791010974
c. Prints 4791001974
d. Prints
5802112085 e. Not sure
Ans: a
58.
#include
<stdio.h>
void
main(void)
{
int i;
for(i=2;i<=7;i++)
printf("%5d",fno());
}
fno()
{
staticintf1=1,f2=1,f3;
return(f3=f1+f2,f1=f2,f2=f3);
}
a. produce
syntax errors b. 2 3 5 8 13 21 will be
displayed
c. 2 2 2 2 2 2 will be displayed
d. none of
the above e. Not sure
Ans : b
59.
#include
<stdio.h>
void main
(void)
{
int x;
x = 0;
if (x=0)
printf
("Value of x is 0");
else
printf
("Value of x is not 0");
}
a. print
value of x is 0 b. print value of x is not 0 c.
does not
print anything on the screen
d. there
is a syntax error in the if statement e. Not
sure
Ans : a
60.
void main
(void)
{
char
arr[100] = {"Welcome to Mistral"};
foo (arr);
}
foo (char
*x)
{
printf
("%d\t",strlen (x));
printf
("%d\t",sizeof(x));
return0;
}
a. 100 100
b. 18 100 c. 18 18 d. 18 2 e. Not sure
Ans :
18,100
61.
#include
<stdio.h>
display()
{
printf
("\n Hello World");
return 0;
}
void main
(void)
{
int (*
func_ptr) ();
func_ptr =
display;
printf
("\n %u",func_ptr);
(*
func_ptr) ();
}
Ans : it
prints the address of the function display
and prints
Hello World on the screen
62.
#include
<stdio.h>
void main
(void)
{
int i = 0;
char ch =
'A';
do
putchar
(ch);
while(i++
< 5 || ++ch <= 'F');
}
Ans :
AAAAAABCDEF
* C++ PROGRAMS *
Note: All the programs are tested under Turbo C++ 3.0, 4.5 and
Microsoft VC++ 6.0 compilers.
It is assumed that,
Programs run under Windows environment,
The underlying machine is an x86 based system,
Program is compiled using Turbo C/C++ compiler.
The program output may depend on the information based on
this assumptions (for example sizeof(int) == 2 may be assumed).
1) 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();
}
Answer:
Say i am in someFunc
Null pointer assignment(Run-time error)
Explanation:
As the object is passed by value to SomeFunc the destructor
of the object is called when the control returns from the
function.
So when PrintVal is called it meets up with ptr that has been
freed.The solution is to pass the Sample object by reference to
SomeFunc:
void SomeFunc(Sample &x)
{
cout << "Say i am in someFunc " << endl;
}
because when we pass objects by refernece that object is not
destroyed. while returning from the function.
2) Which is the parameter that is added to every non-static
member function when it is called?
Answer:
‘this’ pointer
3) class base
{
public:
int bval;
base(){ bval=0;}
};
class deri:public base
{
public:
int dval;
deri(){ dval=1;}
};
void SomeFunc(base *arr,int size)
{
for(int i=0; i<size; i++,arr++)
cout<<arr->bval;
cout<<endl;
}
int main()
{
base BaseArr[5];
SomeFunc(BaseArr,5);
deri DeriArr[5];
SomeFunc(DeriArr,5);
}
Answer:
00000
01010
Explanation:
The function SomeFunc expects two arguments. The first one
is a pointer to an array of base class objects and the second one
is
the sizeof the array. The first call of someFunc calls it with an
array of base objects, so it works correctly and prints the bval
of all
the objects. When Somefunc is called the second time the
argument passed is the pointer to an array of derived class
objects
and not the array of base class objects. But that is what the
function
expects to be sent. So the derived class pointer is promoted to
base
class pointer and the address is sent to the function. SomeFunc()
knows nothing about this and just treats the pointer as an array
of
base class objects. So when arr++ is met, the size of base class
object is taken into consideration and is incremented by
sizeof(int)
bytes for bval (the deri class objects have bval and dval as
members and so is of size >= sizeof(int)+sizeof(int) ).
4) class base
{
public:
void baseFun(){ cout<<"from base"<<endl;}
};
class deri:public base
{
public:
void baseFun(){ cout<< "from
derived"<<endl;}
};
void SomeFunc(base *baseObj)
{
baseObj->baseFun();
}
int main()
{
base baseObject;
SomeFunc(&baseObject);
deri deriObject;
SomeFunc(&deriObject);
}
Answer:
from base
from base
Explanation:
As we have seen in the previous case, SomeFunc expects a
pointer to a base class. Since a pointer to a derived class object
is
passed, it treats the argument only as a base class pointer and
the
corresponding base function is called.
5) class base
{
public:
virtual void baseFun(){ cout<<"from
base"<<endl;}
};
class deri:public base
{
public:
void baseFun(){ cout<< "from
derived"<<endl;}
};
void SomeFunc(base *baseObj)
{
baseObj->baseFun();
}
int main()
{
base baseObject;
SomeFunc(&baseObject);
deri deriObject;
SomeFunc(&deriObject);
}
Answer:
from base
from derived
Explanation:
Remember that baseFunc is a virtual function. That means
that it supports run-time polymorphism. So the function
corresponding to the derived class object is called.
6) void main()
{
int a, *pa, &ra;
pa = &a;
ra = a;
cout <<"a="<<a
<<"*pa="<<*pa <<"ra"<<ra ;
}
/*
Answer:
Compiler Error: 'ra',reference must be initialized
Explanation:
Pointers are different from references. One of the main
differences is that the pointers can be both initialized and
assigned,
whereas references can only be initialized. So this code issues an
error.
*/
7) const int size = 5;
void print(int *ptr)
{
cout<<ptr[0];
}
void print(int ptr[size])
{
cout<<ptr[0];
}
void main()
{
int a[size] = {1,2,3,4,5};
int *b = new int(size);
print(a);
print(b);
}
/*
Answer:
Compiler Error : function 'void print(int *)' already has a
body
Explanation:
Arrays cannot be passed to functions, only pointers (for
arrays, base addresses)
can be passed. So the arguments int *ptr and int prt[size] have no
difference
as function arguments. In other words, both the functions have the
same signature and
so cannot be overloaded.
*/
8.
class some{
public:
~some()
{
cout<<"some's destructor"<<endl;
}
};
void main()
{
some s;
s.~some();
}
/*
Answer:
some's destructor
some's destructor
Explanation:
Destructors can be called explicitly. Here 's.~some()'
explicitly calls the
destructor of 's'. When main() returns, destructor of s is called
again,
hence the result.
*/
9.
#include <iostream.h>
class fig2d
{
int dim1;
int dim2;
public:
fig2d() { dim1=5; dim2=6;}
virtual void operator<<(ostream & rhs);
};
void fig2d::operator<<(ostream &rhs)
{
rhs <<this->dim1<<"
"<<this->dim2<<" ";
}
/*class fig3d : public fig2d
{
int dim3;
public:
fig3d() { dim3=7;}
virtual void operator<<(ostream &rhs);
};
void fig3d::operator<<(ostream &rhs)
{
fig2d::operator <<(rhs);
rhs<<this->dim3;
}
*/
void main()
{
fig2d obj1;
// fig3d obj2;
obj1 << cout;
// obj2 << cout;
}
/*
Answer :
5 6
Explanation:
In this program, the << operator is overloaded with ostream
as argument.
This enables the 'cout' to be present at the right-hand-side.
Normally, 'cout'
is implemented as global function, but it doesn't mean that 'cout'
is
not possible
to be overloaded as member function.
Overloading << as virtual member function becomes handy
when the class in which
it is overloaded is inherited, and this becomes available to be
overrided. This is as opposed
to global friend functions, where friend's are not inherited.
*/
10.
class opOverload{
public:
bool operator==(opOverload temp);
};
bool opOverload::operator==(opOverload temp){
if(*this == temp ){
cout<<"The both are same objects\n";
return true;
}
else{
cout<<"The both are different\n";
return false;
}
}
void main(){
opOverload a1, a2;
a1= =a2;
}
Answer:
Runtime Error: Stack Overflow
Explanation:
Just like normal functions, operator functions can be called
recursively. This program just illustrates that point, by calling
the
operator == function recursively, leading to an infinite loop.
11.
class complex{
double re;
double im;
public:
complex() : re(1),im(0.5) {}
bool operator==(complex &rhs);
operator int(){}
};
bool complex::operator == (complex &rhs){
if((this->re == rhs.re) && (this->im == rhs.im))
return true;
else
return false;
}
int main(){
complex c1;
cout<< c1;
}
Answer : Garbage value
Explanation:
The programmer wishes to print the complex object using
output
re-direction operator,which he has not defined for his lass.But
the
compiler instead of giving an error sees the conversion function
and converts the user defined object to standard object and prints
some garbage value.
12.
class complex{
double re;
double im;
public:
complex() : re(0),im(0) {}
complex(double n) { re=n,im=n;};
complex(int m,int n) { re=m,im=n;}
void print() { cout<<re; cout<<im;}
};
void main(){
complex c3;
double i=5;
c3 = i;
c3.print();
}
Answer:
5,5
Explanation:
Though no operator= function taking complex, double is
defined, the double on the rhs is converted into a temporary
object
using the single argument constructor taking double and assigned
to the lvalue.
13.
void main()
{
int a, *pa, &ra;
pa = &a;
ra = a;
cout <<"a="<<a
<<"*pa="<<*pa <<"ra"<<ra ;
}
Answer :
Compiler Error: 'ra',reference must be initialized
Explanation :
Pointers are different from references. One of the main
differences is that the pointers can be both initialized and
assigned,
whereas references can only be initialized. So this code issues an
error.
No comments:
Post a Comment