Lecture- Variable & Data Types

7/24/2019 Lecture- Variable & Data Types

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Data Types&

Variables

By: Madam Suhada Ishak


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Data Types All C++ compiler support 3 basic data tpye

!amely i!te"er #oati!" poi!t a!d character$

There are ma!y other types o% data e": shortlo!" si"!ed a!d u!si"!ed$

A commo! mistake amo!" !e' C++ pro"rammeris the (ariable is used B)*,) a data types is

assi"!ed to the (ariable$

REMEMBER!!! -ou must al'ays assi"! a datatype to the (ariable be%ore usi!" it$


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A *e' Basic Data Types Table belo' lists data types i! C++$

Data Types Keywords To declarevariable of type

I!te"er i!t I!te"ers e":

33.../01224560

Character char A si!"lecharacter e":7A88988+88m888

Si!"le precisio!#oati!" poi!t

#oat A #oati!" poi!t!umber e": ;$132.$./0$.

Double precisio!#oati!" poi!t

double A #oati!" poi!t'ith doubleprecisio!$

)": ;$55653 3.4


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Variables A (ariable is a data !ame that may be used to store a data

(alue$

A (ariable !ame is chose! by the pro"rammer i! amea!i!"%ul 'ay so as to re#ect its %u!ctio! or !aturepro"ram$

Some e@amples o% (ariable !ames are:

Variables !ames may co!sist o% letter di"its a!du!derscore = ? character but must be"i! 'ith letter$)@amples o% i!correct (ariable !ames are:

Sum Total Average Area_circle

/06 Sum " #$d


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Declaratio$ of %ariables

I! C++ a (ariable must be declared be%ore they usedi! the pro"ram$

A (ariable declaratio! i!%orms the compiler o% the

!ame a!d type o% the data (ariable 'ill hold$

The sy!ta@ %or declari!" a (ariable is as %ollo's:

v_1,v_2,,v_n are the !ames o% the (ariables$

Multiple (ariables o% the same data types areseparated by commas$

Datatype v_1, v_2, v_3,,vn


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&$itiali'atio$ The process o% "i(i!" i!itial (alues to (ariables is

called i!itialiatio!$

C++ permits the i!itialiatio! o% more tha! o!estateme!t usi!" multiple assi"!me!t operators$

)@amples:

@y.m!1.


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De($i$g Symbolic )o$sta$t

I! C++ pro"rams o!e may de!e a co!sta!tusi!" the key'ord Ede!e o! top o% the mai!pro"rams or %u!ctio!s$

The (alue stored i! a co!sta!t ca!!ot be cha!"edduri!" pro"ram e@ecutio!$

A co!sta!t is de!ed as %ollo's:

Ede!e FI 3$;/1Ede!e Day%-ear 360Ede!e GoursFerDay 1/


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*lobal %ariables Hocal (ariables are declared 'ithi! the body o% a

%u!ctio! a!d ca! o!ly be used 'ithi! that %u!ctio!$

Variable ca! be declared "lobally so it is a(ailable

to all %u!ctio!s$

A "lobal (ariable declaratio! looks !ormal but islocated outside a!y o% the pro"ram8s %u!ctio!s$

This is usually do!e at the be"i!!i!" o% thepro"ram le$ The (ariable is !ot declared a"ai! i!the body o% %u!ctio!s 'hich access it$


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Stateme!ts A stateme!t is a complete i!structio! to the

computer$

I! C++ stateme!ts al'ays e!d 'ith a semicolo!=? e@cept %or preprocessor directi(es such asEde!e a!d Ei!clude

Most stateme!t are composed o% e@pressio!s a!d

operators$

)@amples:


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Di+ere$t types of ),,Stateme$t

;$ utput Stateme!t1$ I!put Stateme!t

3$ Assi"!me!t Stateme!t/$ Co!ditio!al Stateme!t

0$ Hoop Stateme!t


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-utput Stateme$t Are used to display i!%ormatio! o! scree!$

The simplest %orm to used cout stateme!ts:

Ei!clude Kiostream$hL

coutKK(alueKK (alueKK(alue

coutKK(ariableKK(ariableK

coutKK(ariableKK(alue

The %ollo'i!" are escape seue!ces 'hich ca! be used i! a

stri!" literal i! a cout stateme!t$! Ne' li!e r Carria"e

retur!O Doubleuote

t Tab % *orm %eed Backslash

b Backspace 8 Si!"le

uote


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&$put Stateme$t These stateme!t are used to read i! i!%ormatio!

%rom a keyboard or other i!put de(ices$

The simples %orm is used to cin stateme!t is:

Ei!clude Kiostream$hL

ci!LL(ariableLL (ariableLL(ariable

The symbol LL is called a! 7e@tractio! operator$

The opera!d a%ter the symbol LL must be a(ariable$


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Assig$me$t Stateme$t Values ca! be assi"!ed to (ariables usi!" the

assi"!me!t operator 77 as %ollo's:

Values ca! be assi"!ed to (ariables at the same

time the (ariable is declared$

Ho'er;.

Ppper;..Step4Total50$61

i!t Ho'er;.i!t Ppper;..i!t Step4#oat Total50$61


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perators A! operator is a symbol that i!structs C++ to

per%orm some operatio!s o! o!e or moreopera!ds$

Gere are the bi!ary mathematical operators:-peratio$ -perator E.ample

Multiplicatio! 9 @9y

Di(isio! Q @Qy

Additio! + @+y

Substractio! 2 @2y

Modulus R @Ry


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-rder of Evaluatio$Arit/matic -perators

-peratio$ -perator -rder of Evaluatio$

Fare!theses =? )(aluated rst$ I% the pare!theses are!ested the e@pressio! i! the i!!ermost

pair is e(aluated rst$ I% there arese(eral pairs o% pare!theses they aree(aluated le%t to ri"ht$

Multiplicatio! di(isio! a!d

modulus

9Q or R )(aluated seco!d$ I% there are se(eralthey are e(aluated %rom le%t to ri"ht$

Additio! a!dsubtractio!

+ a!d 2 )(aluated last$ I% there are se(eral theyare e(aluated le%t to ri"ht$


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E0uality a$d Relatio$al-perators

I! C++ relatio!al operators are used to comparee@pressio!$

A! e@pressio! co!tai!i!" a relatio!al operator e(aluates aseither true =;? or %alse =.?$

C++ !otatio! %or relatio!al operators are listed belo':

-peratio$ -perator E.ample

)ual @y

Not eual @yHess tha! K @Ky

Hess tha! or eual K @Ky

reater tha! L @Ly

reater tha! or eual L @Ly


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E.amplesE.pressio$s Evaluate as &$terpretatio$

/1 . *alse

3L1 ; True

/5 ; True

=0+0? =190? ; True

1 i l2B l


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1ogical2Boolea$-perators

I! C++ these operators allo's the pro"ram totest se(eral relatio!s =compou!d compariso!s? i!a particular e@pressio!$

Belo' are e@amples o% lo"ical operators i! C++:

-peratio$ -perator

A!d &&

r UU

3ot !


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)o$ti$ue44

Het T T,P) a!d **AHS)

Truth table %or the && operator

5 6 5 77 6

T T T

T * ** T *

* * *


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)o$ti$ue44

Truth table %or the UU operator

5 6 5886

T T T

T * T

* T T

* * *


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)o$ti$ue44

Truth table %or the =!ot? operator

5 !5

T *

* T


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E.ample

E.pressio$s Evaluate as i$terpretatio$

=//? && =03? ; true

=/L;? UU =0K1? ; true

=31? && =//? . %alse

=03? ; true


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E.ercise Assume that the (a,IABH)S o%x ; the (alue o%y 6 the

(alue o%z;0 a7k8 b7y8$ Veri%y the output %rom thee@pressio! belo':

E.pressio$s -utput@L && y3

@0 UU y3

=@L5 && y11 UU K/?

aK7a8 && aL78bL7y8 UU b7!8


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E.ercise Assume that the (alue o%x is 1 the (alue o%y is 0 a!d the

(alue o%zis ;0$ i(e the (alues o% (arious e@pressio!belo':

E.pressio$s Evaluate as i$terpretatio$

Lecture- Variable & Data Types

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