electrical engineer notes

8/19/2019 electrical engineer notes

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Operators

Operators are the symbols that are used toperform certain operation on dataC++ provides variety of operator

Arithmetic operator Relational operator Logical operators

Bitwise operators


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Arithmetic operators

The five arithmetical operations supported bythe C++ language are

Arithmetic operator is a symbol that performmathematical operation on dataE ample

+ for addition e.g. a+b- for subtraction e.g. a-b* for multiplication e.g. a*b

/ for division e.g. a/b%for modulo e.g. a%b


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%for modulo

!odulo is the operation that gives theremainder of a division of two values" #ore ample$ if we write%a = 11 % 3;The variable a will contain the value &$ since& is the remainder from dividing '' between

("


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Question

)rite a program that performs allmathematical operation on two variables


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Assignment (=)

The assignment operator assigns a value to avariable" a = 5;This statement assigns the integer value * to thevariable a"The part at the left of the assignment operator ,- is.nown as the lvalue left value- and the right one asthe rvalue right value-"The lvalue has to be a variable whereas the rvaluecan be either a constant$ a variable$ the result of an

operation or any combination of these"The most important rule when assigning is the right-to-left rule% The assignment operation always ta.esplace from right to left$ and never the other way%


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Example

// assignment operator 0include 1iostream2int main -3 int a$ b4a , '54

b , 64 A,bb , 74cout 11 8a%84cout 11 a4

cout 11 8 b%84cout 11 b4 return 54 9


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Compound Assignment

statement An assignment that assign a value to manyvariables is .nown as compound assignmentoperator"E ample

A,b,&5:,y,;,'55


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Compound assignment

Operator)hen we want to modify the value of avariable by performing an operation on thevalue currently stored in that variable we canuse compound assignment operators%C++ provide Compound assignmentOperator that combine assignment operator

with arithmetic operator


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Syntax

,$ ?,$ /,$ @,$ 22,$ 11,$ ,$ ,$ ,-


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Example

int main -3 int a$ b,(4 a , b4 a+,&4 // eDuivalent to a,a+& cout 11 a4return 54 9


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Example

refiB,(4

A,>>B4// A contains &$ B contains &

ostfiB=3;

=B--;

// contains 3! B contains "


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Relational and equalityoperators

Fn order to evaluate a comparison betweentwo e pressions we can use the relationaland eDuality operators"The result of a relational operation is aBoolean value that can only be true or false$according to its Boolean result")e may want to compare two e pressions$for e ample$ to .now if they are eDual or ifone is greater than the other is"


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Example

==#$ual to=&ot e$ual to

'(reater t)an

ess t)an'=(reater t)an or e$ual to

= ess t)an or e$ual to


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Example

, == 5 // evaluates to false. 5 ' // evaluates to true. 3 = " // evaluates to true. 0 '= 0 // evaluates to true. 5 5 // evaluates to false.


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Example 2

a ,, *- // evaluates to false since a is noteDual to *"

a?b 2, c- // evaluates to true since &?( 2, G-is true"

b+6 2 a?c- // evaluates to false since (+6 2&?G- is false"

b,&- ,, a- // evaluates to true"


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Be careful

The operator , one eDual sign- is not the same asthe operator ,, two eDual signs-the first one is an assignment operator assigns thevalue at its right to the variable at its left-

and the other one ,,- is the eDuality operator thatcompares whether both e pressions in the two sidesof it are eDual to each other"Thus$ in the last e pression b,&- ,, a-$ we firstassigned the value & to b and then we compared itto a$ that also stores the value &$ so the result of theoperation is true"


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Logical operators ( !, &&, || )

The Operator H is the C++ operator to performthe Boolean operation =OT$ it has only oneoperand$ located at its right$ and the only

thing that it does is to inverse the value of it$producing false if its operand is true and trueif its operand is false"Basically$ it returns the opposite Booleanvalue of evaluating its operand"


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logical operators && and

The logical operators and are usedwhen evaluating two e pressions to obtain asingle relational result"The operator corresponds with Booleanlogical operation A=I"This operation results true if both its two

operands are true$ and false otherwise"


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Example

The following panel shows the result ofoperator evaluating the e pression a b%

2 #4 24a b a btrue true true

rue false false6alse true false6alse false false


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Example 2

The operator corresponds with Boolean logicaloperation OR"This operation results true if either one of its twooperands is true$ thus being false only when bothoperands are false themselves" Jere are thepossible results of a b%

2 #4 24 b a 77 b

true true truerue false true6alse true true6alse false false


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!or example"

5 == 5 3 ' 0 // evaluates to false true false . 5 == 5 77 3 ' 0 // evaluates to true true 77 false .


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#recedence of operators

)hen writing comple e pressions with severaloperands$ we may have some doubts about whichoperand is evaluated first and which later" #ore ample$ in this e pression%

a = 5 + , % "8e ma9 doubt if it reall9 means:a = 5 + , % " // 8it) a result of 0!

or a = 5 + , % " // 8it) a result of The correct answer is the first of the twoe pressions$ with a result of G"


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Operator Precedence (contd.)Operator Precedence (contd.)Example:Example: 10 * (24 /10 * (24 / (5 - 2)(5 - 2) ) + 13) + 13

10 *10 * ( 24 / 3 )( 24 / 3 ) + 13+ 13

10 * 810 * 8 + 13+ 13

80 + 1380 + 13

9393


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Operator Precedence (contd.)Operator Precedence (contd.)

The order o precedence !n " ++ The order o precedence !n " ++lan#$a#e !% a% ollo&%:lan#$a#e !% a% ollo&%:

'n expre%%!on #! en !n parenthe%!% !%'n expre%%!on #! en !n parenthe%!% !%

e al$ated r%t.e al$ated r%t. Then m$lt!pl!cat!on * and d! !%!on / Then m$lt!pl!cat!on * and d! !%!on /operator% are e al$ated.operator% are e al$ated.

Then pl$% + and m!n$% operator% are Then pl$% + and m!n$% operator% aree al$ated.e al$ated.,n ca%e o parenthe%!% &!th!n parenthe%!%-,n ca%e o parenthe%!% &!th!n parenthe%!%-the expre%%!on o the !nner parenthe%!% &!llthe expre%%!on o the !nner parenthe%!% &!ll

e e al$ated r%t.e e al$ated r%t.


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Operator '%%oc!at! !tOperator '%%oc!at! !t

The order !n &h!ch operator% ha% %ame The order !n &h!ch operator% ha% %ameprecedence are e al$ated !% no&n a%precedence are e al$ated !% no&n a%operator a%%oc!at! !t .operator a%%oc!at! !t ., an expre%%!on conta!n% %ome, an expre%%!on conta!n% %omeoperator% that ha e %ame precedenceoperator% that ha e %ame precedencele el- the expre%%!on !% e al$ated romle el- the expre%%!on !% e al$ated rom

le t to r!#ht or r!#ht to le t.le t to r!#ht or r!#ht to le t.


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Operator '%%oc!at! !tOperator '%%oc!at! !t(contd.)(contd.)

Operator a%%oc!at! !t !n " ++ lan#$a#eOperator a%%oc!at! !t !n " ++ lan#$a#e!% a% ollo&%:!% a% ollo&%:

Operators Associativity() ++(postfx) --(postfx)

e t to r!#ht

+($nar ) ($nar ) ++(pre x) (pre x)

e t to r!#ht

* / e t to r!#ht+ e t to r!#ht

+ * / !#ht to le t


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al$e and al$eal$e and al$e

al$eal$e,t !% an operand that can e &r!tten on the,t !% an operand that can e &r!tten on thele t %!de o a%%!#nment operator .le t %!de o a%%!#nment operator .

al$eal$e,t !% an operand that can e &r!tten on the,t !% an operand that can e &r!tten on ther!#ht %!de o a%%!#nment operator .r!#ht %!de o a%%!#nment operator .


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Example

a = 5 + , % "; might be written either as%a = 5 + , % " ; a = 5 + , % ";


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Example 2

a ,, *- // evaluates to false since a is noteDual to *"

a?b 2, c- // evaluates to true since &?( 2, G-is true"

b+6 2 a?c- // evaluates to false since (+6 2&?G- is false"

b,&- ,, a- // evaluates to true"


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E%cape 5e6$ence%E%cape 5e6$ence% The%e are %pec!al character% $%ed !n control %tr!n# to The%e are %pec!al character% $%ed !n control %tr!n# tomod! the ormat o o$tp$t.mod! the ormat o o$tp$t.7!8erent e%cape %e6$ence% are a% ollo&%:7!8erent e%cape %e6$ence% are a% ollo&%:

Escape Se !e"ceEscape Se !e"ce #!rpose#!rpose a a 'larm 'larm ac %pace ac %pace ;orm eed ;orm eed n n "arr!a#e ret$rn "arr!a#e ret$rn t t Ta Ta < < 5!n#le 6$ote 5!n#le 6$ote = = 7o$ le 6$ote 7o$ le 6$ote


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$ype casting

The process of converting the data type of avalue during e ecution is .nown as typecasting

Two types of type castingFmplicit type castingE plicit type casting


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%mplicit type casting

Fmplicit type casting is performedautomatically by the c++ compiler"


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,mpl!c!t T pe "a%t!n#,mpl!c!t T pe "a%t!n#

,t !% per ormed a$tomat!call "++,t !% per ormed a$tomat!call "++comp!ler. e.#. char + >oatcomp!ler. e.#. char + >oat >oat>oat

long double

double

long

float

int

char

Jighest data type

Lowest data type


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Explicit type casting

E plicit type casting is performed by theprogrammer Ft is performed by using cast operator The cast operator tells the computer toconvert the data type of a valueKynta

type- e pression


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Example#loat a$bFnt c4

A,'5"(B,*"&c, int-a @ int-b4Cout11c4

ResultKhows 5


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$he si eof operator

The si;eof operator is used to find the si;e of anydata valueFt gives the number of types occupied by the value

KyntaKi;eof operand-

E amplecout11si;eof int-Result

&


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comments

Comments are line of program that are note ecutedCompiler ignore comments and does notinclude them in e ecutable programComments can be added anywhere inprogram in two ways

Kingle line comments !ultiline comments /? ?/


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Basic Input/Output

The standard C++ library includes the headerfile iostream$ where the standard input andoutput stream obMects are declared"


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Standard %nput

The standard input device is usually the.eyboard" Jandling the standard input in C++is done by applying the overloaded operator

of e traction 22- on the cin stream" Theoperator must be followed by the variable thatwill store the data that is going to bee tracted from the stream" #or e ample%int age4 cin 22 age4


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Example

include 1iostream2 int main - 3 int i4 cout 11 8 lease enter an integer value% 84

cin 22 i4cout 11 8The value you entered is 8 11 i4cout 11 8 and its double is 8 11 i?& 11 8" n84 return54 9


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'a( )or*

)rite a program that adds two floating pointnumbers and shows the sum on screen)rite a program to calculate and print thearea of a sDuare


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C++ ,anipulator

C++ manipulator are used to format theoutput in different styles"The manipulators are the most common wayto control output formatting

EndlKetwKhowpoint


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Endl manipulator

The endl stands for end lineThe endl manipulator is used to move cursorto the beginning of ne t line

E ampleCout11Nhello 11endl11Ncomsats


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"on%tant%"on%tant%

,t !% a 6$ant!t that cannot e chan#ed,t !% a 6$ant!t that cannot e chan#edd$r!n# pro#ram exec$t!on.d$r!n# pro#ram exec$t!on.

T&o t pe% o con%tant%. T&o t pe% o con%tant%.!teral con%tant!teral con%tant

5 m ol!c con%tant5 m ol!c con%tant


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!teral "on%tant!teral "on%tant

,t !% a al$e that !% t ped d!rectl !n a,t !% a al$e that !% t ped d!rectl !n apro#ram.pro#ram.;or example;or example

!nt a#e 19 ?!nt a#e 19 ?

T pe% o !teral "on%tant% T pe% o !teral "on%tant%,nte#er con%tant,nte#er con%tant e.#. @Ae.#. @A

;loat!n# po!nt con%tant;loat!n# po!nt con%tant e.#. 10.22;e.#. 10.22;"haracter con%tant"haracter con%tant e.#. B'


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5 m ol!c "on%tant%5 m ol!c "on%tant%

,t !% a name #! en to al$e% that cannot,t !% a name #! en to al$e% that cannote chan#ed.e chan#ed.

,t can e declared !n t&o &a %.,t can e declared !n t&o &a %.con%t D$al! ercon%t D$al! er

con%t data t pe !dent! er al$e ?con%t data t pe !dent! er al$e ?e.# con%t !nt F 100 ?e.# con%t !nt F 100 ?

7e ne 7!rect! e7e ne 7!rect! e

G de ne !dent! er al$e ?G de ne !dent! er al$e ?e.# G de ne Pl 3.141H93 ?e.# G de ne Pl 3.141H93 ?


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Expre%%!onExpre%%!on

,t !% a %tatement that e al$ate% to a,t !% a %tatement that e al$ate% to aal$e.al$e.

,t con%!%t% o operator% and operand%.,t con%!%t% o operator% and operand%.e.#e.# ' + ?' + ?

Operator

Operands


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#ro$ra%

G!ncl$de I!o%tream.hJ o!d ma!n() K

char ch1- ch2- %$m?ch1 B2< ?ch2 BL< ?%$m ch1 + ch2 ?

co$tIIC5$m CII%$m?M


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O!tp!t

104eca$%e '5",, al$e% o B2< and


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#ro$ra%

G!ncl$de I!o%tream.hJ G!ncld$eIcon!o.hJ

o!d ma!n()K

clr%cr()?%hort ar1 32ALA?co$t II ar1 II endl?

ar1 ar1 +1 ?co$t II ar1 II endl?

ar1 ar1 1 ?co$t II ar1 II endl?#etch()?

M


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O!tp!t

32&'&- 32&'832&'&

eca$%e ran#e o %hort !% 32AL@ to32ALA.


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#ro$ra%

G!ncl$de I!o%tream.hJ G!ncld$eIcon!o.hJ Gde ne P, 3.141

o!d ma!n()K

>oat r- area?clr%cr()?co$t II CEnter rad!$%:=?c!nJJ r?area 2.0 * P, * r?co$t II C'rea C II area?#etch()?

M


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O!tp!t

ser i $ive i"p!t t,e" Area ie .isp aye. o" t,e scree"


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#ro$ra% 0include 1iostream"h2 0incldue1conio"h2

void main -3

clrscr -4int a$b4

a , '54b , *4cout 11 Na+b ,N11 a+b 11 endl4cout 11 Na>b ,N11 a>b 11 endl4cout 11 Na?b ,N11 a?b 11 endl4cout 11 Na/b ,N11 a/b 11 endl4cout 11 Na@b ,N11 a@b 11 endl4getch -4

9


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O!tp!t

a+ 15a- 5a* 50a/ 2a 0

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