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Ppl unit 1 and 2 decode scan

Computer Engineering (Savitribai Phule Pune University)

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comme tn to
stng
loop

Control
Veriebles
Inslde
the for
Labeled
Continue).
String
Handine
String
and
Loop Breab

ProgrammingLanguage
iabeted

using Java
Stetements

1
Encapsulation

methods
astia
gning Syntax and Semantics
Polymorphism,

Inhertance,
declaring
objects
V constris.
UNIT
fundementals.

returning
& ralue. ructon
MethodsCles
class. methode
to t
Cesses end methods orerloeding
Puh
addtng
rertables
finalire0
method.

control. final. nested

static. final

nts Inherttarcesthe
reference
colection eccess

objects
kerrord
gerhage returning
rarieble-length
arguments
Language and Software DevelopmentEnvironments
obiect as
perameter.
erquments. Using super. multu
1.1:
pesting ine references.

commend
clas
method
de
clesses super dynamic
tmner
ftware development process.
tnheritence.
orerriding.
and method
package term software
Member
acoess

cal sequence Interfeces: Defining a 1 Define the

end (defn
sequential combination of
constructor

interfaces
hiererchy

ining is a
Software development process
Pacbages packages,
cles
ebrtract
ciesses
Obiect
protection.
Importng
ding
extending inter
inte
nterface well defined starting and ending points and
access intertaces,
CLASSPATH in Ans. at
each having
end rariebles
pecheges
nesting
appiring). phases, each
tmpiementetior

there are identifiable

deliverables to the next phase.
tnstence of operetor phase
each
in Java software development process in brief.
UNIT VI Exception Handling catch. throw. throws, finel Explain
ay. Q.2
exception ypes. uncaught
exceptions,
exceptions.
exceptions.
custom except
exception
Fundementel built-in
cleuses nested ty
statements.
Streams. byte Streams and Ans.
multiple catch Vo:
our own exception
sub ciasses).Managing console input. Writng Console analysis
Requirement

& specification
creeting Reading
Streams.
Characte Streems Predetined
Fundamental. Applet Architecture, Appler
Output Print Writer ciass.Appiet Apple:
HTML Applet tag. passing parameten
L Sofwaredesign
status window. and specification
Sbeleton. Requesting Repeinting. Program.
to Appiets Difierence
berweer Applet and Application
Implementation

Verification
and validation

Testing

Maintenance

process
Fig.Q.2.1 Phases ofsoftwaredevelopment
(1) Requlrements Analysis and Specification
documented in
identified and
The requirements of the system are
this phase.
a document
which is
requirements are then documented in
nese(learntech2215@gmail.com)
Downloaded by Harshad Pakhale (SRS).
popularly known as Software Requirement Specification
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1-2 Pyog LenguageSmtarand Se

PPL
Sofhware Design and Specification 1-3 Prgramntng LamgusgeSynterend Semania
(2
and specificati 1.2 Languageand Software
The SRS is used during the softwaredesign ation Destgn Methods
During this phase. various
software modules and their interfa
ImportantPoints to Remember
designed The programminglanguages have some programmingconstructs
3) Implementation using which particular software design method canbe
impiementation is a phase in which the coding i5 done in suitah implementedeasily.
languagewith the help of design document. Some languages can be
programming implemented with the heip of objects.
Idealy it shoukd be simply mapping of software design intot Such languages are called object oriented
programming
coresponding code. language. For example-C, Java
4 Verification and Validation SimilaryPascal or C are structured programminglanguages.
03 What do you mean by
This phase is for checkingthe quality
programmingparadigm?
ofthe software system being Ans.: The programmingparadigm
representsa specific programming
deveioped style suitable for implement specific software design methodd
Verificeion means "Are we
building the product right?" and Q4 Explain the stylesofsoftwaredesign.
validaion mezns "Are we buildingthe right product". Ans.
(5) Testing Procedurai programming

Testing is a process offinding bugs or errors from the Functionaiprogramming

system.
(6) Maintenance
Abstract data type programming
After delivering th software sysem to the user, there Software
for changes in the sysem due to Some are chances design Modue based programming
methods
soTe dditional funcionality. malfunctioningor due to
Object onented programming
.This cost of maintenarce is always higher than all other
softwaredevelopmentphases. the Generic programming

Decaratve programming
Fig Q.4.1 Styles of software design
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nd Seman
Programming LanguageSyntaxand
Se.
1-4
PPL
Programmng LanguageSyntaxand
Semantics
Programming
1he focus of this stv PPL 1-5
1)Procedural and functions.
programming language is on
procedures
1.3 Languages and ComputerArchitecture
style is
(2)Functional
Programming: This programming
The expressions.
mainly
ma.

Points to Remember
functions.
and ns Important
applicable for of mathematical
use
architecture in computer is
blocks of this programmin The most commonly used computer
building
functions are the primary
Haskell, ML are
the examples similar to Von Neumann architecture.
Programming languages like of CPU, Memory Unit,
The Von Neumann architecture consists
functionalprogramming
When the abstract data type Input deviceand Outputdevice.
(3)AbstractData Type Programming: CLU Q.5 Explain with diagram
style is used.
the relationship between languages and

is the unit of programming modularitythen this

architecture.
used of this type of programming, computer
programming languagemakes
Ans.
this style of programming,the
(4)Module Based Programming: In Programmers need
fundamental unit is module. Each module is comprised of Requirements

variables, functions, procedures and so on. These modules can be Programming languages
primarily usedexport the services from one module to another.
to
Modula-2 and ADA are two commonly used programming Imperative languages

languages that use module basedprogramming

(5)0bject Oriented Programming : The emphasis of this style is Procedural Module Object Generic
Towards
high level
based oriented
objects. Examples are C+, Java, ADA-95 and so on. programming

(6)Generic Programming : In this type of programming style, the

generic modules are instantiatedduring compile time or Functional programming
run time
and various entities like data structures, Tunctions or
proceduresare Logic programming
created.

(7)DeclarativeProgramming:In this styleof programming,there is Constraints

declarative description of problem instead of
algorithmic Von Neumannarchitecture
implementation.For example Logic programmingtechnia1e
-

in programminglanguage like can machine architecture

be implemented PROLOG. Fig Q.5.1 Programming languagesand
Conventional programminglanguagesare implementedon the Von
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Neumann architecture. These languages are also called as Von
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1-6 ProgrammingLanguageSyntaxand
and SemaN
PPL
Programming LanguageSyntax
andSemantics
used for these lann. 1-7
Neumann languages.
The other termms
languages or
statementbased
u lan anguages PPL
the algorithm of the program
languao3) Simplicity: Due simplicity increases the readability of
to
can

the
also called as state based The simplicity
of these languages is goingto be expressedeasily.
The systematic development
program.
high level of abstraction. constructs that should be
There are some programming
other type oflanguages (4) Safety: is harmful in
Along with the imperativelanguages For example use of gotos
strictly prohibited.
*sustrictly reduce the flexibility and

as Functional and Logic programmingg

languages also execu.
are These features may
Clprogramming
on Von Neumann architecture. FollowingFig. Q.5.I representsreadabilityof the program.
which
relationshipbetween languages and computerarchitecture. Robustness: Robustness is a feature of a
program
(5) undesired events in program. In
deal with
14 ProgrammingLanguageQualities provides the ability to suitable
undesirable situations, the event is trapped and
some
so that system becomes predictable
response can be programmed
Q6 Write and explain various language qualities that promote for the m
reliability of a language.
1undesirablesituations.
achieve the efficiency.
Ans. Q.7 Explain how any language can

Languagequalities
Ans.:
More execuion speed

Writability Readability Simplicity Safety

Robustness
Fig. Q6.1 Language qualitesthat Less memory consumption
support rellablity
(1)Writability Efficiency
can
It is a be achieved
property of expressinga program in a Ost
most natural Reusability
Writability should focus on problemsol
Wntability should focus on problem natural way.
way
not be distractedby solving activity and should
language details.
(2)Readablity Portability
Due to English text and familiar notations
tions the readah Fig.Q.7.1 Language and efficiency
programminglanguagesis increased. For exampleddability of
statements there is a use of if-then-else conditional The most desired feature of a languageis efficiency.The basic goal
the loopingg statements there are construct.Fo
of such
for,while and repre
do-whiesenting of efficiency is program execution should be faster and it should
programming constructs enhance the reada loops.Use consume less memory.
understandability of the program. bility and Other aspects of efficiency are reusability and portability.
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nfax and
ProgrammingLanguageSyntarand SemaPPL ProgrammingLanguageSyntaxand
Semantics
1-8 1-9
PPL used to
the software develo the rules that are

Reusability : For languageefficiency

that
elope
PEtQ.9
e sdefine
are
What is syntax of a language ? Explain
the syntax of a language.
such components
interested in developing define the form
always
Ans.: Syntax is defines as a collection of rules that
for other applications.
Portabilityis a
feature by which the programofa language. of rules: lexical
.Portability: is defined by two set
other
m The syntax of language
a
modified to work on platfom
work on one platformcan be
rule and syntactic rules.
Perspective and Early specific word classes.
That
1.5 A Brief Historical
The lexical rules affect in particular
High Level Languages of characters that
rules specify the rule for set
means, the lexical
scanf,
form a word. For example do, if, print,
-

can be combined to
level language along with their. use lexical rule.
Q.8 Enlist any four high
are all keywords in C.
This can be specified using the
purpose. which defined the particular
The syntactical rule has a wider scope
Ans.
defined by the lexical rule.
arrangement of words
Language Originator Year Purpose the context free grammar
For specifying the syntax of a language
COBOL Committee 1960 BusinessData Processing is used.
with the help of suitable
Q.10 Explain the concept of syntax diagrams
Pascal N.Wirth 1971 GeneralPurpose
example.
the lexical rule and syntactic rules
D. Ritchie 1974 System Programming Ans.: Followingexample shows
for a simple program containing a_signment
statements only.
ADA J.Ichbiah 1979 General Purpose,
Embedde syntactic
ynt Rule
System
program> := { <statement>*}
statement> :=<assignment>
<assignment> :=<identifier>=<expr>;
1.6 Language Definition
Kexpr>:=<identifier>| <number> |(<expr>)| <expr> <operator>
<expr>
Importantpointsto Remember Lexical Rule
Every programming language has two major Com
Syntax and Semantics. ntsoperator> :=+|-|°|/|<|>|<=|>=
<identifier> :=<letter> <ld>*
Syntax represents form of a language | <digit>
kld>: <letter>
Semantic representsthe meaningofaDownloaded
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PPL 1-10 ProgrammingLang1uageSyntar o

nd Sem
<number> := <digit> +
PPL 1-11 ProgrammingLanguageSyntaxand SemanticCS
<letter::= a|blc|...|z For example consider the C code fragment
<digit> := 0|1|2|....|9
The above rules can be represented using syntax diagra for(i=0;i<=10;i++)

The non terminals are represented by circles.

ram
Terminals are represented by boxes.
Now consider Pascal Code fragment for for loop
For i=0 to 10 do

program -0 Begin

End
Thus these two constructs differ only at lexical level
statement concrete syntax specifications incude
Concrete Syntax : The
and keywords that allow parser a to construct aan
the tokens
statementassignment abstract syntax tree unambiguously. The concrete syntax tree will

retain all the information of input

assignment
identferE
0+ expr For example
expr Consider the context free grammar
expr operator expr E: E-+E
E= E*E
identifier E:num
The expression 2*3+4 can be derived aas

number

expr

Fig. Q.10.1:Syntax
-0-
diagrams
Q.11 What is abstract syntax and
conerete
suitable examples. syntax ? Abstract syntax Concrete syntax
Ans.
Explain w tree tree
Abstract Syntax:
When the two
lexical level then it is said that constructsdist
theyhave abstractsyntax,
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unguage Syntar.
ntax and Se
Q.12 Explain axiomatic and denotational
example.
emantics with
sema.

Semantics
1-13 Programming Language Syntaxand
Ans.: 1) AxiomaticSemantic PPL
Let,
.The axiomatic semantic is a semantic that is that is appropriatb a = expr
arguing program correctness. semantic will be
assignment statement. Then denotational
be an
An axiomatic semantic consists of specified as
f) error for undefined variable in expr.
i) A language for stating assertionsabout programs. i) dsem (a:
=
expr, =

result
expr, f) =

i)dsem (a:
=

i) Rules for establishingthe truth

ofassertions. two statements S1 and S2 to be executed as

The assertionscan be made Ifthereare

by using a triple called Hoare .
for example Hoare Thi 1 $1;52
<Pre> C <Post> dsem (S1, 1 = f1.

Where C is a command <Pre> and

represents f1) 2
dsem(S2,
=

condition before execution of precondition ie.

command. The
postconditioni.e. the conditionafter executionof<Post> representss dsem ($1:S2,undefined
1)1 variable
..hle error will be propagated.
error will
For example command. For any propaga
{b 5) Q.13 What is pragmatics?
a5 b+2 a> 1) formal specification of
Ans. Pragmatics does not affect the
focuses on design ofa
programming languages. However, pragmatic
Precondition Command that it would be easy to read,
programming language in such a way
The
preconditionsand postconditionsPostconditon
are write, and modify efficiently. Pragmatics
describes how to use the
2. Denotational semantic
presented in braces.
This is another
language prac situations.
language in practical
method of Forexample:
This method based on scribing semantic
recursivefunctions of programs. if(a>b)
.For example Consider an instead of predicate.
instead aat10;
expr. The function assignmentstatemene for
f(expr) gives eror ifif itit is In above code there is single
be executed hence statement to ,
we

than single line statements

variablex present in expr. Otherwise is
undefined expression
apression used {}.
have not used t But if therenot are more

will ined, for same then have to

result of evaluationwill be expr Or sam then we have to enclose them within {}. There are chances to forget
returned. be en we
evaluatedand toadd brackets for execution of multiple
statements. Hence
line statement also within
pragmaticallyC allows execution of single
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.
DECODE Less than gHOTOca
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PPL 1-14 ProgrammingLanguageSyntax and.s

and Sema
Q.14 : - 2*y +1 1-15 ProgramumingLanguageSyntaxand Semantics
yX-3 2.15 Gtve advantagesand disadvantagesof interpretation.
ns.
0
Compute weakest precondition for given
assignment statement,
Advantages
Ans.: For the given assignment statements y < 0) is assod.
a. Modificationof user program can be easily made and implemented
postcondition.
as execution proceeds.
Let y:X-3
.Type of object that denotes a variable may change dynamically.
but y <0 is given posteondition.Substinuungl l0r
cuauon 1,w, Debugging a program and finding errors is
get
simplified task for a

program used for interpretation.

X-3 < 0
.The interpreterforthe languagemakes it machine independent.
X<3
Weakest preconditionfor first isadvantages:
assignmentstatement.
Now consider . The execution of the program is slower.
x: 2*y+1 ..Memory consumptionis more.
Substitute x<3 for equation2,
2*y+1 < 3
2.16 What is translation?
Ans. Translation is a process in which the high level program is
2y< 2
translated into the machine language code before getting executed.
y<I Weakest precondition for second assignme The high level languageslike C, C++need
statement. translaion.
Q.17 Explain language processing using translation.
1.7 Language Processing,Interpretation,
Translation,the Conceptof Binding
Ans.: The process oftranslation
is performedin followingsteps-
I. The program modules are separately translated into relocatable

ImportantPointsto Remember machine code. This translator is called as compiler.

.Languageprocessingcan be performed sing These translated modules are linked together in a relocatable unit
1.
Interpretationand Translation. two alternatives This task is carried out by linker or linkage editor.
-

During interpretationof a language, every .Finally the complete program is loaded into the memory as
instructionis
executed. directly executable machine code. This task is carried out by loader.
Translatorscan be compilersand
assemblers
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Programming LanguageSyntax and Seman 1-17 ProgrammingLanguageSyntaxand Semantics

1-16 PPL
PPL Source
The interpreters do not The compilers produce
program 2.
produce object code. object code.

The compilers
Complier

3. Merit: The interpreterscan Demerit:

Relocatable
the
be made portal because they has to be present
on
machine code

do not produce object code. host machine when

Linker particular program needs
Single relocatable
to be compiled.
unit

4. Merit Interpreters are Demerit: Thecompileris

Loader and it
simpler and give us a complex program
Executable
improved debugging requires large amount of
unit
environment. memory.
Output data
Inputdata Interpreter
(executed Q.19 Explain the concept of binding.
result) variables,
Ans. Any program contain various entities such as

using translation and These entities have special

Fig.Q.17.1:Language processing
so on.
routines, control statements
called attributes. For example
techni properties. These properties
are
uses the combined two
The modern translation technique has number of
or function
-translation and then interpretation.That means the codethe programming entity routine
source
of parameter passing methods and so
translated into intermediate code and then the intermediate code parameters, type parameters,
on. Specifying the nature of attributes is called binding.
interpreted.
data called
Q.18 Diferentiate betwen- Interpreterand compiler. The attribute description is stored in a structure

Ans. descriptor.
Sr. No. The binding can be of two types static binding and dynamic
Interpreter Compiler
1.
binding
Demerit The source Merit: In the process When the attributes are bound at program translation time then it is
program gets interpreted
compilation the prog called static binding.
every time it is to be is
analyzed only once a When the attributes are bound at program execution time then it is
executed, and every time the then the code
source called dynamic binding.
program is
analyzed. generated. Hen
Hence interpretation is
efficient than Ca
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Programming Lang
I-18
PPL 1-19 ProgrammingLanguageSyntaxand Semantics
PPL 1.81.8 Varlables

In above code, there are three variables namely a,b and c. These
variables have the scope for entire function sum0. Outside the
Remember

Important
Points to function sum), these variables are not visible or accessible.
of memory
memory in which
which

a name
for
reserved
area
som 2) Type
Variable is
be stored.
value can
an
can be modified
modified with
with the hel
help Type can be defined asspecificationof set of values that can be
variable
The values in associatedwith a variable. For example -

assignment statements.
char s;
attributes of variables
Q.20 Explain various Here the variable s is of type character. That means it allows the
Ans. value range from -128 to 127

Various attributes of
variables are The language defines its in-built set of data types. These types are

Name and Scope called primitive types.

1)
the declaration statem. 3) 1-value
The variablename is introduced during
For examplein C The term lvalue originally referred to objects that appear on the left
int a; (hence the 1') hand side of an expression. An lvalue represents an
Here the variable namea is specifiedat declaration statement. object that occupiessome identifiable location in memory

The scope of the variable is basically the area of instructions For example
nt x
which the variable name is known. The variable is visible under1
name within its scope and is invisible under the name outside Here variable x is a lvalue, because it is an object with an
scope. For example identifiable memory location.
void main()
4) r-value
sum(); The value is encoded value which can be stored in the location
r
}
void sum) associated with the l-value variable. The encoded representationis
interpreted according to the variable's type.
int a,b.c; For example
a=10;b=20; int x
c=a+b;
K=(3+4);
printf"inThe sum= %d",c); The value of (3+4) represents the r-value.
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Syntax and
Language Syntax
and SemeyPPL 1-31 ProgrummingLangnageSymtaxandSemanties
Programming
setuat
varinbles
? parameter
unnnmed
votd main ()
PPL
What are
referenee
mnd
are
those
variables that
hat can
Q.21
variables Such a
unnaned variable.
Declarafon
Am. The
r-value of another
void aum (inta, int b|
accessed
through

called as reference.

be
accessed using pointer to poin sum (10, 20) Call
can
variable
unnamed
The
variable declare a variable of noi.

we can
In pascal the up-arTo void sum (int x, int y)
For exampie rrow
defined by pretixing
type is
integer. The pointer
with the base type. formal parameter
caret symbol (") named type because int 2
a is of Defnitton
/here variable
type a integer /accompanied with type
printi'Addition %d"', z)
and pointed by a
allocate an unnamed integer variable
We can

of type a
Q.23 Explain the positional method of binding.
newlaPtr): //unnamed varnable
for
The languages like C, C+ allow pointer
to rerer o namAns.: Most of the programminglanguages use positional method
binding actual to
variables.For example-
voidmain()
intx=6.//integer named variable formal parameters Actual parameters
nt "ptr. //pointer vanabie in routine call.
ptr=&x //using & the referencevariableis represented. Following Sum (a, b, c) Functlon call
1.9 Routines FigQ.23.1 Binding of
represents formai and actual
parameters
Q.22 What are routines ? Explain how routines can be handled ? positional method
Functdon definiton
Ans.:Routine is a collection of instructionsthat can be use of binding in which oid
sum
(intx, int y, int 2)
perform specific task and can be repeatedly executed. For examp is parameter a is
Functions in C, Assembly language Formal parameters
subprograms,the subroutines bound to parameter
in FORTRAN, Proceduresand x, parameter b is
Functionsin Pascal and Ada.
The routines are usually handled by three ways bound to parameter
i) Declarationii) call y and so on. Fig. Q.23.1 Positional method of binding
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ii) definition For
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Programmlng
Language nd Sem
Syntar an

1-22 PPL 1-23 ProgrammingLanguageSyntaxand Semantics

routines.

PPL of generic
the
concept which implementsthe
implements
the des 1.10 An Abstract Semantic Process
.24 Explain
routine isa
routine

concept
the concept of
of gen
In C++,
Am.:Generic

data type.
using
general .26 Write short note on abstract semantie processor.
algorithm templates.

outine is
achieved by using above code can be
code can imn
be implemen Ans.: The abstract semantic processori is an abstract processor
C++ the above
In
kor example
follows describing the operational semantics of programming
used for
routine as
using generic
languages.
template <class T>
.It consists of instructionpointer, memory and processor
T add(T a. Tb) The memory is a part where the instruction is executed and data to
be manipulated are stored. The memory is divided into two parts -
TC
Ca+b code memory and data memory. The code memory is denoted by
return c; array C[location_Index] and data memory is denoted by array

Q.25 What is aliasing? Explain with

suitable example. D[location_Index
which twodife The C[I and D[!] denote the values stored in Ith cell of code and
Ans.: Definition: Aliasingis a mechanism by data memory respectively.
names are associatedwith the same entity. The concept of alias
is exactlyopposite to that of overloading. The instructionpointer(ip)always points to the code memory(C)
The modificationof value stored at
For example particularcell is done using the
instructionset.
void fun(int &a)
The read instruction is used to read the value îrom
input device
cout << "Value is:" <<a; and write is used to write the instructionsto the
output device.
For example
void main()
set 50, read
int x = 10; The meaning this command is read from the
val input device and is stored
fun(x) at location 50
10 1024 102
set write, D[20]
Here two different 1024 1090 1090
variables x The meaning of this command would be value stored at
and a point to the location 20
i.e. 10
same value will be transferredto the
int val;
output device.
The aliasing can be easily The jump instructionis used to
val 10; modify the usual control flow. The
achieved using int a &val; val,a,b ard alises jump instructionhas two
example
pointers for int b &val;
versions jump (unconditionaljump) and
-

jumpt(basedon condition)
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Fig. Q.25.1
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Syntar and

1-24
Programming
Language
Semam
polnter PPL 1-25 ProgrammingLanguageSyntaxand Semantics
PPL
Instruction

Memory
instruction
pointer | Hence there are three allocation methods used during run time
The the
to structure. These are
points
always
code
instruction in the 1. Static allocation The static allocation is for all the data objects at
memory. compile time.
Following Fig. Q,26.l
2. Stack allocation In the stack allocation astack is used to manage
machine shows abstract
the run time storage.
machine Code memory Data memon 3. Heap allocation In heap allocation the heap is used to manage
the dynamic memory allocation.

Fig.Q.26.1
Abstract semantic processor 1.12 Case Study: Run Time Structure of C

1.11 Run Time

Structure Important Points to Remember
The run time structure of C makes use of static, stack and heap
Q.27 Explain the run time structure. allocationtechniquesdepending upon the programmingentities.
executionof any program, compilerdemands
the During the runtime execution of C, the activation record is
Ans.:During
block of memorv
block of memory to operating system. This maintained.
called run time storage. U There are four methods of parameter passing - 1. Call by value
The run time storage is subdivided Codearea 2. Call by Reference 3. Copy Restore 4. Call by Name
to hold code and datasuch as Q.28 Consider following C code fragment and represent runtime
i) Code memory for generated Staticdataa execution structure for abstract semantic machine.
area
code. voidmain ()
ii) Data memory which stores data
objects and Stack int a,b;
information
which read_data(a, b) ;
keeps track of procedure if (a < b)
activations. The data memory is
divided into aa+b ;
else
a) static data area
Heap a a-b
) Stack print (" % d", a);
TOp
c)Heap Downloaded by Harshad Pakhale (learntech2215@gmail.com)
Fig. Q.27.1 Run time structure
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Language
and Sema
Syntaxand
Programmlng

1-26 code
without ree. PPL 1-17 ProgrammimgLanguageSyntaxand Semanties
forward
PPL straight for abstract
is a straignllocated for abstract semang. Temporary values s.
The temporary variables are needed during
code is a allocated

Ans.: The given statically

Q.28.1.
can be following
Fig. the evaluation of expressions. Such variables are stored in the
code
Hence the represented
by
be Date memory (D) temporary field of activation record.
machine It can
Code memory (C)
cell for a 2. Local variables The local data is a data that is local to the
set0, reed
cell for b execution of procedure is stored in this field of activation recor
set 1, reed
Saved machine registers This field hoids the information
jump 4, D[O]<
D[1 Instrucion regarding the status of machine just before the procedure is called.
pointer
set 0,D0-D[1
This field contains the machine registers and program counter
4. Control link This field is optional. It points to the activation
set write,D0
record of the calling procedure. This link is aiso called dynamic
link.
Fig Q.28.1:Execution of code on abstract semantic machine 5. Access link This field is also optional. It refers to the non local

makes use of a d data in other activation record. This field is aiso cailed static link
For stack allocation technique, C program
record. field.
structure popularlyknown as activation
Activation record. 5. Actual parameters This field holds the information about the
Q.29 Write short note on -

Ans.
actual parameters.These actual parameters are passed to the called

The activation record is a block of

Return value procedure.
used for managing Return values This field is used to store the result of a function
memory Actual parameters
information needed by a single call.
Control link
esecution ofa procedure. (Dynamiclink) |2.30 By taking the example of factorial program explain how activation
ecord will look like for every recursive call in ease of factorial (3).
In C the activationrecord situated in Access link
is (Staticlink) ns.
stack area. The contents of
activation Saved machine nain()
record are as shown in status
the
Fig Q.29.1. Local variables
int f;
t factorial (3);
Various fields of
activation record are
Temporaries
as follows Jnt factorial (int n)
Fig. Q.29.1 Model o,
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(n=1)
activation record
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PPL retum 1;

else (n-1)
PL 1-29 Programming LanguageSyntaxand Semantics
factorial

return (n oncept Activation tree: Activation tree is a data structure used

or specifying the flow of control
among the procedures. In an
ctivation tree
Step1: main
Each node shows an activationof procedure.
Act
Local ) For showing activationof main
record program root is used.
for main it)If lifetime of 'x' occurs before the lifetime of y then x becomes left
child of y.
Return value To vIf control flows from x then 'x'is parent node of
to y
y'
calling 2.31 Write the output of the
following C program using following8
Act
Act. parameter 3 procedure arameter passing methods.
record )Call by value. i) Call by reference.
for factorial Dynamic link
i) Call by value-resultand iv) Call by name.
#include<stdio.h>
int i= 0;
First call intj = 0;

Step 2 void pint x, int y)

Step 3
Act
record for main
main
Local xt=1;
Loca
Act
factorial it=1;
acora record for
factorial (3))
Returm value yt 1;
ord for
acorai
Ream aiue Parametar 3
3 Parameter Dynamicink
Dynamic ink factorial void swap(int x, int y)
Act
accnai record for Retunvalus
factorial (2) Parameter13
Retun va
record DynamicEnk* X=Xty;
Parameter 2
factoria
Dynamicink y X-y
Act Retum valel
record for
factorial (1)
Parameter XI-y
Second call Uynamicink

Third call
main)
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1-30 ProgrammingLanguageSyntax
PPL and Sene
{1, 1}; 1-31 Programming LanguageSyntaxand Semantics
inta12 PPL
int b[3 {1, 2, 0} x1,y-0. The x and y values get swapped. But on returning
pali), a[i]); main, the x and y values do not get preserved.
printf"%d, %dn", a[0},a[1); is for printing b[o] and b[2] values. Therefore
The printfstatement
Swapj.a]) we will get 1 2 0.
printf"%d.%d, %dn", bj0], b[1], b[2); Hence output will be
return 0; 1
1 2 0
Ans.: i) Call by value
When Plali], ali] ) is called then
i) Call by reference
formal parameters get associated with
P(1.1) In call by reference, the
actual parameter.
P(x.y) void p(int x, int y)
In the function body P, xand y will be increment. Hence x =
2 "/
i- 2, y 2. But on
x+ 1 x becomes 2, y becomes
=
returning to main, the x and y values will not i+ 1 i= 1/
preserved. y+ 1 y becomes 3 /
printf(" %d %d", a[0], a[1] ) will resultas 11
When control returns to main a[0] = x = y =3 and a[1] remains as
When call to swap (j, a[ji] Dgiven it will be
it is i.e. 1.
swap (x, y) After calling swap function the printf statement is printing b[0],
swap (0, 1) b[1] and b[2] i.e. 1, 2, 0.
In the function body of x Hence output will be,
x X+y 3 1
i.e x 0+1 =1 1 20
yx-y l) Call by value result
y 1-1 =0
xX-Y In call
by value result the actual parameter applied by the caller is
x 1-0 copied into callee's formal parameter the function executes and then
X formal parameter is copied back to caller. No alias or reference is
created between formal and actual parameters.Hence
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PPL vntax and Semant

void plint x, int y)

2
{
al0] x, a[0] y Structuringof Data,
i.e.
X+ 1
X1+1=2
Computationsand Program
yt 1
i.e. y 1+1 2
2.1 Buitin and PrimitlveTypes
On returningg to main value of x gets copied to
a[0].. afo. al0] ImportantPoints to Remember
The a[l] remains 1. After swap function tne printr prints
d[u}, b[1]a. Any programming language has
b[2). predefined set of built in
data
Hence output will be, types.
2 1 Programminglanguage support various built in data types such as
1 20
boolean, character, integer and reals.
v) Call by name
Q.1
Explain buit in types of programminglanguages.
In this method the actual
parameters will be Ans.: Any programminglanguage has a predefinedset ofbuiltin data
substituted for all tnes
occurrences of formal
parameter. ypes This built in data type reflects the behavior of underiying
Hence hardware.
p( int x, int y) Due to
builtin data type, the values are interpreteddifferently
plalol,a[1D using hardware instructions.

X+ 1 Following are the types of built in types of programming

i+= 1 Becomes al0=1+1 2 languages.
i+ =0+ 1 =1 1. boolean: Thisdata type define only two values TRUE and
y+1 FALSE. In Boolean algebra the Boolean data type is used.
al1 1+1 2
The basic operations performed are and, not, or.
On returning fromP we get 2,2 as
an output of first 2. character:
printf prints b[0], b[1] and bl21,printf. charactervalue
After calling swap, the The single is representedusing
char data type. In C the charactertype variable is
Hence output will be,
2 2 char choice;
120 3. integers: Integer value can be specified using maximum
and minimum limit. In C there are four types of integer
specifications int, short, long and char
(OGCOnro
END..
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Date, Copetaion
4 reas: The real numbercan be
representedusing
exponent model. In C. the floating Strcurimg Dete.Computatioms&Program
representedusing float data type. point
num The examples of cartesian product constructors in programming
02 What is primitive dats type languages are struetures in C. reeords in Pascal and COBOL
Ans The primitive data pes are elementarydata 0.4 What is finite mapping ? Erplain intensionai and ertensional
types
ESw mapping. .mepping
not buit from some other
types. The values of primitivedata Ans.Finite mapping is
data type a function in which domaintype is mapped
stomic and cannot be decomposedinto simpler to values of range type
constituents
Mary times the built in data types can be The finite mapping is done using two techniques- intensional and
with buit in data type but there are interchangeabh extensional mapping
exceptions. For example .

mCisapimitivedata type which is used to define new constamThe intensional mapping is a routine in which the range type
values are directly associated with domain type values.
22:DataAggregatesand Type Constructors
Finite Mapping

ImportantPolnts to Remember
Programming languages allows the
objects aggregation of elemente
ro
Intensionai Mapping ExtensioraiMapoing
Ing the object certain constructors are provided. T The extensional
resultingobjects are called compound mapping is routine in whicn ra pe a tne

.For example - objects. values are associated as data aggregates. For exampie int a(S].
s
similar date type
elements Constructoris aggregation Here integers from subrange 0 to 4 are mapped althougn tnis
declaration does not specity which element corresponds to the
Q.3 What is Cartesian
constructor? product ? How it is particularsubrange.
useful to denote
Ans.:
D In extensionalmapping using indexing technique the
In extensional elements are
The cartesian u*s
productof n sets A, Aj, For example
AAg As xA, is whose el
Aj, A,
A, denoted
A, denoted mapped in given subrange.
A xA, is
a set
set whose
a
elements
...,

2 wherea, belongsto A are ordered n-tuples for (i 0;i<s, i)

The caresian a li=i+ 10

product is also used to denote the
For example construct@
type constructo,
pe Elements 10, 11, 12, 13 and 14 are associated with locations a[0],

int int> int al1], a[2]. a[3] and a[4] respectively

Explain the concept of abstract data type.

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Structuring ons
Data, Coputatlons
&
2.4 ProyN r 2-1 Structurtngof Data,Computations&Program
PPL is Let use define some important terminologies that are associated
abstract data type
Ans.:An
objects with type system
1. A set of data data objecte
on those
abstract
operations 1. Type: The type can be defined as a specific set of values and
2.A set of the data objects and operat
eration particular set of operations that can be applied to such values.
of both
the dat.
3. Encapsulation
3. Er
that user
cannot
manipulate
2. Object or data object: The data object
such a way definecd. can be defined as location in memory with
the use of operations
without assigned name. Refer Fig Q.6.1.
of information hiding, Fig. Q.6.1 Data objectx
facility
Encapsulation
provides the
packages and
in C++,JAVA, Visual i Basi 3. Type error: The illegal operation that manipulate the data
Examples -In ADA
classes facilitate
the abstract
data type. objectsare called type error.
denotes the abstras
ract
in C++ which 4. Type safe or type secure: The operationor a programis said
Following is an example
to be type safe if all the operationsin a program are guaranteed
type to always apply to data of the correct ype. Thus in type safe
class student
operationsno type error will occur.
private Q.7 Differentiate between static and dynamie type checking
int RollNumber,
Ans.
fioatmarks
public: Sr.No. Static Type Checking DynamicType Checking
void input_data();
void display_data(); 1. Staticchecking is a kind of | Dynamic checkingis a kind
checking which is done at of checking which is done
The operations input_data(and display_data)are intended compile time. at run time.
manipulateRolINumberand marks data objects. The data obje For example- In C, C++ the For example - In Perl and
and operationsare 2.
encapsulatedby class. static type checking is Prolog the dynamic type
2.3:Types Systems performed. checking is performed.

Q.6 Explain the concept of 3. The static type checking is The dynamic type checking
type systems.
Ans.: Definition: also called as compile time | is also called as execution
The type system is defined as set of rules use
the languageto structureand time checking.
organizeits collectionof varioustyp | checking.
Type systems play
semanticsof a languagc.
an
important role in determining
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2-6
Computatons
Structuring ofData, &Progre
PPL 2-1 Strueturtngof Data,Camputations&Program
PPL The dynamie
The dynamic type chec. PPL
type checki
detection of
of
For example: Consider a code segment as follows
allows
without brings
brings flexibility typedef struct Node
errors
programming program design.
program
to this
code. Due int x
running the
can be
detected
erors node;
many node 'first, 'second;
and
reliably
quickly, struct Node "last1, "last2,
automaticaly In the above code the variables first and second are name
The checking informati
increases the compile time similarly variables lastl and last2 are name equivalent. But
t need to be kept maintain.equivalent
overhead. and lastl are not name equivalent as the names for these two
during the execution, Th:irst
causes extra Gto Dype expressions are different. Although all the four variabies first
second,last1,last2 are similar under structural equivalencesince they
requirement
duringare representingthe same type pointer('struct Node).
execution of program.
Structural Equivalence
Q8 What ib strongtypesystem? When two expressions are the same basic ype or formed by
that guarantees no
Ans.: The strongtype system is a type system then
to generate type errors. Alanguage wth strongtype system 1S saikapplying the same constructor to structurally equivalent types
are called structurallyequivalent.
to be strongly typed language. A type system is said to be weak ithose expressions
s not strong. Hence a language with weak type system is said t For example:
be weakly typed language. struct student
There are static type system which are the strong type systems{
The static type system is a type system in which type of ever nt i
expression is known at compile time. char name| 10];
Q9 What is type compatibility?
struct employee
Ans.: A strict type system in
which one operand with type A
allowed to perform operation with another hint ID;
operand with type B. 1char name|101:
feature is called type compatibility.
Q.10 Explain name and structural student s1;
Ans.: Name Equivalence
equivalence.
employee e1;
If we write
In the
equivalence the type expressions are given th
name
names. Hence two type then it is said to be valid, because sl and el are structurally
expressions are saidDownloaded
to be name
byequivalen
Harshad Pakhale (learntech2215@gmail.com)
and only if they are identical. sl and el are structurallyequivalent.
quivalent.Thus
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Structuring of Data, tations &Prog

Computations

2-8 2-9 Structurtngof Data,Computations&Program

PPL
coercion? one type to
rting one to a aubtypeNEW_SUBTYPEis NEW_INT range 12..55;
Q.11 What is
convertin
of
process
is the convere.. 2.4: The Type Structure of C++, Java
Ans. Type
coercion rsions implicit nversion
: impli
conversions

of
types
two
There are
explicit conversion.
Coercion a.13 Write short note on type structure of C++.
Ans. : The type
structure is divided into two main categories
of C++
- Fundamental types and Derived Types.
Explicitconversion
The fundamentaltype is integer and float. The integer data type
-

Implicit conversion

Two types ofconversion is classified into int, char, short, long. The float data type is
Fig.Q.11.1
automaticallyby the compiler
then classified into float and double
conversion is done conversions are also
If the conversion. The
implicit call The derived type of actually derived from the fundamental types-
is called implicit conversion there
is no loss of inform and pointers
coercions. In this type
of
but not vice versa For example, arrays, class, structure, union, functions
as converted to float
can be
for example integer to float there is no los pointers
conversion from integer
means in from float to i C Typestructure
information but for converting
the information
te
there is a loss.
to be explicit if the programn
The conversion is said Fundamentaltypes Derived ype
one type to another.
specificallywrites something converting
for

For example Foat Claes vt Union Pointer

int xyz,p;
integer
p-(loat)xyz;
The identifier xyz is type-caste and this is how explit Cr Shor ngot o
of C++
conversion from int to float takes place. Fig. Q.13.1 Type structure
Q.12 What is subtyping ? elements. For example
but usua Arrays is collection of similardatatype
* A
BuDpe 1s a new type based on a parent type
int al10]; It will create an array of 10 integer elements
with a more restricted range. It inherits all of the characteristics o to create
The class, and union allows the programmer
structure
parent type and in addition, it can be freely intermixedwith the par class is well known entity in
C++ by
user defined data types. The
type in calculations and assignmentstatements. members and member functions
in
which one can encapsulate data
For
example followingcode defines the concept of subtyp
-

C++. For example

type NEW_INT is new INTEGERrange 12.55;
type NEW_INT_TYPEis new INTEGER; class stack
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Structuring f Data, nutations «

Computatio
2-10 2-11 Structurlng of Data,Computations&Program
PPL of
PPL to represent an expression? Explain it with the help
o16 How
private:
suitable example.
int s/10);
Expressionsare powerful and natural way for representingthe
Ans.:
int top
sequence of operations.
public:
void push(int item)
of expression is a tree
The effective way of representation
int pop();
representation.

data structure using class,

class.
creates a stack For example
class
The above
short note on type
structure of Java. 19+(10+3 7)/(20-3*2)
Q.14 Write in two Consider an expression
classified two categ0
The type of Java is
structure
() first.
Ans. will evaluate
2. Derived Types. Step 1:We
1. Built in Data Types * 7=21. Thenperform 10 21 31.
Javedat type structure
Step2: Evaluate3
Step 3: Evaluate 3
** 2=9. Then20-9 11.
Buit-in Compoete 31/11 =2.
Step 4:Perform
+2=21.
Floaengpol Class ATaye Stpe 5: Perform 19
The tree representation will be

Byte Char Shot Long Float Double

Fig. Q.14.1 Types structure of java

The builtin Data Types8:
19
Various data types used in Java are
byte, short, int, long, ca
float, double and boolean.
10 20
2.5:Expresslonsand Statements
ImportantPoints to Remember of expression
The program is structured
into different units Fig. Q.15.1 Tree representation
for computation. Q.16 What is conditionaltargets?
These units are useful for
branchinglooping and decisionmak Ans..SOm support the
conditional
in programs.
ueeision makAns. Some programming languages
For example in C the tertiary operator is
There are various control statement using operator.
structures used by the For example if a >b
-

conditional statement.
switch case, for, if then program h used to specify the
else, while and so gn
do Downloaded by sucu
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Comyutattons.

2-12
Structuring of Data,
written
&Prog PPL 2-13
Structuringof Data,Computations&Program
PPL

otherwise b this
statement
can be
sing
usi.
i) Procedures
ii) Functions
then a a kind
Procedure is ai of routine that does not return
as
follows- a value. On the
conditional expression
(a>b)?a.b other hand, functions return a value.
written as ides both procedures and functions. The formal
Pascal provid
In ML it is else b
a
Ifa> b then can be-by value or by reference.
parameters
par

Procedure in Pascal
Example of
Procedure
MaxNum (x, y: integer, var z : integer)
Execution and Iteration
2.6:Conditional
begin
if x>ythen
controls.
forms of statement level
Z: X
Q.17 Explaindifferent
controls
forms ofstatementlevel else
-

Ans.: There are three

1. Composition: The statements

execute in the order theyapn end;
on the page.
Example of Function in Pascal
2. Alternation:Two sequencesform alternatives.At a time on
Function MaxNum (x, y integer):
: integer; ( returningmaximum
one sequenceis executed and not both. between two numbers )
3.
3. Iteration: Some set of statements are repeated over and ove var

again.
result integer
begin
if (x > y) then
2.7: Routines
result: =x
else
ImportantPoints to Remember
Routines are collection of statements that are
result:= y:
to be MaxNum: = result;
repeatedly. execute
end
Routines are of two types
Proceduresand Functions 2.8:Style Issues:Side Effects and Allasing
-

Using call and return instructionsthe

routines are handled. non-locals, parameter passing by
.19 Explain the side effects of
a.18 What are referenceand of aliasing.
proceduresand functions ?
Ans.: Most Ans.Side effectof non-locals:
of the programming each unit has
routines languages support two types 1)If large number of non-locals
are used and

non-locals then these program

unrestricted access to
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2-14
Strucmringof utations& Pro
Data,Comwpntao.
PPL
difficult to read,
understand and modi
dify.
in
Ther 2-15 Structurtngof Data, Computatlons&Program
becomes
might be
modified n
chances that the variables onl
nono Thus assignment to one variable affect the value in another
ariable.
environment.

of error
due to unrestricte
unrestrine.

2) Finding
ermors or
cause
use 2.9: Exceptions
non-locals become complex.
reference ImportantPointsto Remember
passing by
Side effect ofparameter Definition
Definition of
of Exception Excenti
Exception: Exception can be defined as an
the actual parameter
might get modis
There are chances that undesirable condition that occurs in the program.
reference.
passingby' Definition of Exception Handling: Exception handling is
to parameter
Side effect of function : As procedures do not return a value, mechanism by which the language can recognize the unexpected
a
, the
are less side effects of procedures. However, there are seriousSisundesirable and anomalous behavior and specify the response

effectsoffunction.Forexample codethatmust beexecutedwhen the exceptionis raised.

Q.20 Explain exception handling mechanism in C++
result: a + fun(a, b) ;
Ans.:C+ exception handling mechanism makes use of three
.In above statement, if function fun uses parameter passing keywords try, catch and throw. The try represents the block of
reference, then fun might produce a change in a or b 1) T statementsin which there are chances of occurring some
reduces the readabilityof program. exceptional conditions.
2) Another side effect is such statements prevent compileWhen exceptiondetectedit is thrown using the throw statement.
from generating optimized code. There exists a block of statements in which the exception thrown is
handled appropriately. This block is called catch block
Side effect Aliasing:The two variables are
of said to be
they share the same data object during unit activation.For aliasesi Following figure illustrates the concept of exception handling
consider followingcode firagment exampk mechanisms - mechanisms-
EQUTVALENE (A, B) thraw
A 100 Call to the
function that|
Thus variablesA and B are contains
set to
values A and B exception try throws
Now, if we add
B
followingstatements block excepton
200
WRITE(,)A
The above statement catch
will print 200 block
instead of 100.
Fig. Q.20.1 throw-try-catchmechanism

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Strmctring f Data, rions &Prop

Comyutations

PPL

3
2-16

For example Structuringof Program

C++Program
#include <iostreamn>
using namespacestd 3.1:ConceptsIn Supportof
void main () Modulartty
try Important Pointsto Remember
Software module is used in abstraction.
throw 100:
Variousfunctionality that support the concept of
catch (int x) such as encapsulation, interfaces, separate
such
modularity
compilation
cout <<"An exceptionat
"
<< x << endl;
mechanism, creating library of modules and so on.

Q.1 Explain the concept of encapsulationwith suitable

erample
Ans.
An
Output
exceptionat 100 Definition of Encapsulation: Encapsulationis a mechanism
which the program
by
components can be combined together to
provide some specific functionality.
END..
Encapsulationsupports for informationhiding of implementation
of the modules.
In C++, the encapsulationis provided by means of a class. For
instance
class Test

private: Encapsulated data members and

int a,b member functions in a single unit
public: called class.
int add(a,b);

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