Program Elements and Structure

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PROGRAM ELEMENTS ANDSTRUCTURE



Objectives

To know the basic elements that is used to consal!oithms

To undestand the natue o" each elements To detemine the basic stuctue that will be use

"omulate al!oithm



Program Elements

Thee basic elements o" al!oithm ae as "ollows Constants $aiables E%&essions



Constant

A liteal 'alues that does not chan!e duin! &o!ae%ecution( )t is *%ed 'alue



Types of Constant

+( Numeic Constant , ma- be an inte!e o ea

Chaacteistics

a( Commas and blank s&aces cannot be included wiconstant

b( The constant can be &eceded b- a minus si!n

c( The 'alue o" constant cannot e%ceed s&eci*ed and ma%imum bounds( .o each t-&e o" constant/ theswill 'a- "om one com&ile o" a &o!am to anothe



Types of Numeric Constant

+(+ )nte!e Numeic Constant

, a whole numbe/ it has an e%act 'alue and doecontain decimal &oint

E%am&le#

The "ollowin! ae ille!al numeic constant

+0/111 ille!al chaacte 2/3

+4 56 78 ille!al chaacte 2blank s&ace3

587,+11,544 ille!al chaacte 2,3

90 -17005000



Types of Numeric Constant

+(5 Real Numeic Constant

, numbe that contains a decimal &oint o an e%both:( )t has a&&o%imate 'alue

E%am&le#

The "ollowin! ae not 'alid eal constant

51 Eithe a decimal &oint o an e%&onent must b

+/546(15 ille!al chaacte 2/3

3.30 415.05



Types of Constant

5( Chaacte Constant

, a sin!le chaacte/ enclosed in an a&osto&he ;uotation maks:

E%am&le# ‘F’ ‘w’ ‘7’ ‘*’ ‘’



Types of Constant

7( Stin! Constant

, consist o" an- consecuti'e chaacte enclosed;uotation maks

E%am&le# “Fee”“wi” “790”



Variables

)s a &otion o" the com&ute<s main memo- use

a numeic o a stin! constant )t e&esents a cetain 'alue The 'alue stoed in the 'aiable ma- be chan!e

&o!am e%ecution

)t can onl- hold one 'alue at a time



Rules in Defining a Variable Name

Must contain onl- lettes/ numbes and=o an undescoe 2>3

Must be!in with a lette Undescoe must not a&&ea consecuti'el-

Must be uni;ue

Must not be a ke-wod o ese'ed wod o" an- &o!ammin! la

E%am&le#

The "ollowin! ae not 'alid

NO STUD ille!al chaacte 9blank s&ace:

6ct does not stat with a lette

MA>>LE undescoe a&&eas consecuti'el-

S Sum Num1F_Name



Types of Variables

+( Numeic $aiable

, contain data o hold numeic 'alue onl-

T-&es o" Numeic $aiable

a( )nte!e Numeic $aiable ? holds inte!e 'alue on

b( Real Numeic $aiable ? holds eal 'alue onl-

5( Chaacte $aiable, contain chaacte 'alue onl-

7( Stin! $aiable

, contain o holds stin! 'alues onl-



Expressions

A !ou& o" &o!am elements consistin! o" o&e

o&eatos O&eands ? can be a constant o 'aiable O&eatos ? can be an aithmetic and elational

E%&essions alwa-s -ield a 'alue o" a cetain t-&de&endin! on the t-&e o" e%&essions

T-&es o" e%&essions Aithmetic E%&essions Stin! E%&essions

@oolean E%&essions



Aritmetic Expressions

An e%&ession consistin! o" numeic constants o

'aiables se&aated b- an aithmetic o&eato w-ields a numeic 'alue

The !eneal "omat o" a numeic e%&ession is a

E%am&le#

operand operator operand opoperand

4 * !

4 and ! are operand"* #perator $%u&tip&i'ationS(m)o&



Aritmetic Operators

Operator Purpose

+ Addition

- Subtaction

* Multi&lication

/ Di'ision

% Modulus Di'isionModulus Di'ision ? di'ision in which etuns the emainde &otion

10 + 3 , 19+ 10 ,

17 + ! , 1




ow to detemine the t-&e o" an aithmetic e%&

+( Combinin! somethin! o" t-&e rea& withsomethin! o" t-&e eithe inteer o rea& aesults to rea&5( Combinin! an-thin! with di'ision si!n alw-ields to rea&

7( Combinin! two thin!s o" t-&e inteer eiaddition 9B:/ subtaction9,: o multi&lication-ields to inteer t-&e8( Placin! a minus si!n 9,: in "ont o" anaithmetic e%&ession does not chan!e its t




Real and inte!e will -ield eal 'alue

Di'ision will -ield eal 'alue

)nte!e Di'ision 9it tuncates the emainde &at o" the ;

!.0 / 1 , 3.0!.0 1 , !.0!.0 - 1 , 1.0!.0 * 1 , !.0

!.0 1.0 , !.0!.0 1 , !.0

! ! , 1

5 ! , !



Complex Aritmetic Expressions

Numeic e%&essions can be mi%ed to contain se

o&eands and o&eatos( Paenthesis can be used to !ou& a cetain &oti

e%&ession

/ ! !, / ! !, / 1.0, 7.0

$3 / 4 *10 , $3 / 4 *10, 7 *10, 70

10 * 4 * , 10 * 4

!.0, 40 !.0,



Prece!ence Rules Aritmetic Expression

Ode o" e'aluation

+( )" &aenthesis ae &esent/ then the- detemthe ode o" o&eation5( )" the ode is not detemine the &aenthesis/ =/ o&eations ae e'aluated *st be"oe B

7( )" thee is still the ;uestion o" which o&eatiodo *st/ the com&ellin! o&eations in thei le"t i!ht ode



Aritmetic Expression " Or!er of Evaluation1. !0 4 * 9 +3

, !0 4 * 9 +

3 , 5 * 9 +3

, 45 +3 , 0

!. 5 * 3 5 * 10 - !

, 5 * 3 5 * 10 - ! , 15 5 * 10 - , 3 * 10 - !0 , 30 - !0 , 30 2 40 , -10

3. - $15 2 / 10 *$ 11 / , - 7 / 10 *$ 11 / , - 7 / 10 *17

, -7 / 170

4. 5 * $1! * 10 $!5 , 5 * $1! * 10 5 , 5 * $1!0 5 , 5 * !4 , 1!0



#tring Expression

Consists o" stin! constants o stin! 'aiables se&aated b- o&eato which -ield to stin! 'alue

The !eneal "omat o" a stin! e%&ession is as "ollows#

E%am&le#

Stin! e%&ession use onl- one o&eato/ the B o&eato( The eeco&eato on stin! is concatenation

Concatenation , a&&endin! the 'alue o" the stin!

operand operator operand operoperand

, “e"u" ” , “wi&& ”6 , “uide u"” ,‘ ’ , / / 6

, “e"u" wi&& uu"”



$oolean Expression

E%&ession which -ields eithe TRUE9+: o .ALSE Eithe a Relational E%&ession o Lo!ical E%&ess



Relational Expressions

@oolean e%&ession consistin! o" numeic o sti

e%&essions/ numeic o stin! 'aiables and numstin! constant se&aated b- elational o&eato

The !eneal "omat o" a elational e%&ession is "ollows#

@oth o" the o&eand must be o" the same t-&e/ teithe both numeic o both stin!

The o&eand can be a numeic o stin! e%&essnumeic o stin! 'aiable o numeic o stin! c

operand operator operand



Relational Operator

Operator Purpose

> Geate than

>= Geate than e;ual to

< Less than

<= Less than o e;ual to

<> Not e;ual to



Relational Expressions

Rules in e'aluatin! Relational e%&essions#+( Fhen e'aluatin! a elational e%&ession/ the 'alu

o&eand is com&aed to the 'alue o" the i!ht o&eadetemine whethe the entie e%&ession is tue o "5( )" the o&eand is 'aiable/ then coes&ondin! 'alused "o com&aison7( )" the o&eand is a numeic o stin! e%&ession/ t

e%&ession is e'aluated *st to detemine its *nal 'abe used "o com&aison8( )" a &otion o" numeic o stin! e%&ession is 'a

its coes&ondin! 'alue will be used to ai'e at *the said e%&ession

4( Fhen com&ain! stin! 'alues/ each chaacte o



Relational Expression

8ate , 100

ota&_6S , 50ota&_: , 46omte'; , 40Name" , “#< #N =>”

8e&ationa& ?@pre""ion :nterpretation

8ate A 5ota&_6S B A ota&_:ota&_6S B A 40Name" B A “rnie”“6S” A “CDC”

“#E” , “do”

8D?

8D?

8D?

8D?FS

?FS



%ogical Expressions

An e%&essions consistin! o" one o moe elatio

e%&essions se&aated b- the lo!ical o&eato theithe TRUE o .ALSE

The "ollowin! ae the lo!ical o&eatos# NOT AND OR



%ogical Expressions

To e'aluate lo!ical e%&ession/ tuth table must

N# rut; a)&eN# rue ,FS?N# Fa&"e ,8D?

N rut; a)&erueN rue , 8D?rueN Fa&"e , FSFa&"e N rue ,FS?Fa&"e N Fa&"e ,FS?#8 rut; a)&e

rue#8 rue , 8D?rue#8 Fa&"e , 8D?Fa&"e #8 rue , 8D?

Fa&"e #8 Fa&"e ,



%ogical Expression

Conside the "ollowin! 'aiables and its 'alue#6S , 15: , 0N%? , “=6”< , 500

8D?8D? N

,8D?

1. $6S A,10 N $6SB,!0

!. $: , 1 #8 $: ,!

FS?

FS?

#8

, FS?

3. N# $N%? ,

FS?N#,8D?

4. $<A 500 #$<B400

FS?

#8

FS? #8,8D



&ierarcy or Priority of %ogical Operator

E%&essions in &aenthesis .ist

NOT Second

AND Thid

OR .outh



%ogical Expression

Conside the "ollowin! 'aiables and its 'alue#

, 1N%? , “#N”H6 , 100

1. $,1 #8 $,! #8$,38D? FS

?FS?

#8

#88D? #8

FS?,8D

?

!. $N%? , “#N” N N# $$A,50N$B,1508D? FS

?8D?N$

N#

N $FS

?

N#

8D? N

8D?N8D?,

3. $N%? ,“#N” N $H6A,508D? 8D?N

8D? #

,8D?

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Program Elements and Structure