Operators anjavascriptd Operands

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Operators and Operandsmental Java Operators

uction

ration is an action performed on one or more values either to modify the value held by

both of the values, or to produce a new value by combining existing values. Therefore, an

on is performed using at least one symbol and at least one value. The symbol used in an

on is called an operator. A value involved in an operation is called an operand.

operator is an operator that performs its operation on only one operand. An operator is

to as binary if it operates on two operands.

Colon;

i-colon is used to indicate the end of an expression, a declaration, or a statement. As we

n in other sections, there are other uses of the semi-colon.

Brackets { }

ackets are used to create a section of code. As such they are required to delimit the

of classes and other statement, such as conditional statements. Curly brackets are also

create variable scope. We will see various examples.

heses ( )

st computer languages, Java uses parentheses to isolate a group of items that must beed as belonging to one entity. For example, parentheses are used to differentiate asuch as mainfrom a regular variable. Here is an example:

eses can also be used to isolate an operation or an expression with regard to another

n or expression.

e Brackets [ ]

brackets are mostly used to control the dimension or index of an array. We will learn how

hem when we study arrays. Here is an example:

lass Exercise {

ic static void main(String[]args) {

mma ,

mma is used to separate variables used in a group. For example, a comma can be used to

Operators/Ope

C#

C++

Visual Basic
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he names of variables that are declared with the same data type. Here is an example:

lass Exercise {

ic static void main(String[] args)

String firstName,lastName,fullName;

mma can also be used to separate the members the arguments of a method, as we will

hem.

tical Learning: Introduction Operators

rt the NetBeans IDE

the main menu, click File -> New Project...

the first page of the wizard, click General. In the Projects list, make sure that Java

plication is selected and click Next

the Project Location, accept the suggested path or type a new one, such asPrograms\JavaLessons.

the Project Name text box, type Operations1

ck Finish

m what we have learned so far, change the file as follows:

ckage operations1;

blic class Main {

public static void main(String[] args) {

String customerName, homePhone;

int numberOfShirts, numberOfPants, numberOfDresses;double priceOneShirt, priceAPairOfPants, priceOneDress;

int orderMonth, orderDay, OrderYear;

double mondayDiscount;

}

ve the file

signment =

ou declare a variable, a memory space is reserved for it. That memory space is filled with

. To "put" a value in the memory space allocated to a variable, you can use the

ent operator represented as =. Based on this, the assignment operation gives a value to a

Its formula is:

Name= Value

ableNamefactor must be a valid variable name. It cannot be a value such as a number or

e-quoted) string. Here is an example that assigns a numeric value to a variable:

lass Exercise {

ic static void main(String[] args) {

double salary;


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/ Using the assignment operator

alary = 12.55;

variable has been declared and assigned a value, you can call print() or println() to

ts value. Here is an example:

lass Exercise {


double salary;

/ Using the assignment operator

alary = 12.55;

System.out.print(salary);

uld produce:

ve code declares a variable before assigning it a value. You will usually perform this

ent when you want to change the value held by a variable. Providing a starting value to a

when the variable is declared is referred to as initializing the variable. Here is an:

lass Exercise {


// Initializing a variable

double salary = 12.55;

System.out.print(salary);

that you could declare various variables at once by using the same data type but

ng their names with commas. When doing this, you can also initialize each variable byg it the desired value before the comma or the semi-colon. Here is an example:

lass Exercise {


/ Initializing various variables when declaring them with the same data type

ouble value1 = 224.58, value2 = 1548.26;

ystem.out.println(value1);

ystem.out.println(value2);

uld produce:

tical Learning: Assigning Values to Variables


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use the assignment operator, change the file as follows:

ckage operations1;

blic class Main {

public static void main(String[] args) {String customerName, homePhone;

int numberOfShirts= 5, numberOfPants= 2, numberOfDresses= 8;

double priceOneShirt= 0.95D, priceAPairOfPants= 2.95D,

priceOneDress= 3.25D;

int orderMonth = 3, orderDay = 15, orderYear = 2002;

double mondayDiscount = 0.25; // 25%

}

ve the file

Quote '

gle quote is used to include one character to initialize, or assign a symbol to, a variable as char. A single qoute is usually combined with another single-quote and a character

ncluded between them. Here is an example:

lass Exercise {


char gender;

gender = 'M';

System.out.print(gender);

include only one character between single-quotes except if the combination of symbolsvaluated to one character. This is the case for escape sequences. Here is an example:

lass Exercise {


char gender;

gender = 'M';

System.out.print(gender);

System.out.print('\n');

Quotes "

ble quote " is used to delimit a string. As mentioned for the single-quote, the double-

usually combined with another double quote. Between the combination of double-quotes,include an empty space, a character, a word, or a group of words, making it a string.

an example:

lass Exercise {


tring message;


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essage = "Welcome to the wonderful world of Java";

ystem.out.print(message);

e-quoted string can also be declared and then assigned to a variable.

tical Learning: Using Quotes

use single and double-quotes, change the file as follows:

ckage operations1;

blic class Main {

public static void main(String[] args) {

String customerName = "James Burreck",

homePhone = " (202) 301-7030 begin_of_the_skype_highlighting

EE (202) 301-7030 end_of_the_skype_highlighting";int numberOfShirts = 5, numberOfPants = 2, numberOfDresses = 8;

double priceOneShirt = 0.95D, priceAPairOfPants = 2.95D,

priceOneDress = 3.25D;

int orderMonth = 3, orderDay = 15, orderYear = 2002;

double mondayDiscount = 0.25; // 25%

System.out.println("-/- Georgetown Cleaning Services -/-");

System.out.println("========================");

System.out.print("Customer: ");

System.out.println(customerName);

System.out.print("Home Phone: ");

System.out.println(homePhone);

System.out.print("Order Date: ");

System.out.print(orderMonth);System.out.print('/');

System.out.print(orderDay);

System.out.print('/');

System.out.println(orderYear);

System.out.println("------------------------");

System.out.println("Item Type Qty Sub-Total");


System.out.print("Shirts ");

System.out.print(numberOfShirts);

System.out.print(" ");

System.out.println(priceOneShirt);

System.out.print("Pants ");

System.out.print(numberOfPants);


System.out.println(priceAPairOfPants);

System.out.print("Dresses ");

System.out.print(numberOfDresses);


System.out.println(priceOneDress);


System.out.print("Monday Discount: ");

System.out.print(mondayDiscount);


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System.out.println('%');

System.out.println("========================");

System.out.println();

}

ecute the application. This would produce:- Georgetown Cleaning Services -/-

======================

stomer: James Burreck

me Phone: (202) 301-7030 begin_of_the_skype_highlighting FREE (202)

1-7030 end_of_the_skype_highlightingder Date: 3/15/2002

----------------------

em Type Qty Sub-Total

----------------------

irts 5 0.95

nts 2 2.95

esses 8 3.25----------------------

nday Discount: 0.25%

======================

sitive Operator +

uses a type of ruler to classify numbers. This ruler has a middle position of zero. The

s on the left side of the 0 are referred to as negative while the numbers on the right sidelers are considered positive:

-6 -5 -4 -3 -2 -1 1 2 3 4 5 6 +

0

-6 -5 -4 -3 -2 -1 1 2 3 4 5 6 +

on the right side of 0 is considered positive. To express that a number is positive, you can

+ sign on its left. Examples are +4, +228, +90335. In this case the + symbol is called a

perator because it acts on only one operand. The positive unary operator, when used,positioned on the left side of its operand, never on the right side.

thematical convention, when a value is positive, you don't need to express it with the +

r. Just writing the number without any symbol signifies that the number is positive.e, the numbers +4, +228, and +90335 can be, and are better, expressed as 4, 228,

Because the value doesn't display a sign, it is referred as unsigned.

ess a variable as positive or unsigned, you can just type it. here is an example:

lass Exercise {


ystem.out.print("Number = ");

ystem.out.println(+802);

uld produce:


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802

gative Operator -

can see on the above ruler, in order to express any number on the left side of 0, it must

ended with a sign, namely the - symbol. Examples are -12, -448, -32706. A value

anied by - is referred to as negative. The - sign must be typed on the left side of theit is used to negate. Remember that if a number does not have a sign, it is considered

Therefore, whenever a number is negative, it MUST have a - sign. In the same way, if

nt to change a value from positive to negative, you can just add a - sign to its left.

an example that uses two variables. One has a positive value while the other has a

value:

lass Exercise {


ystem.out.print("First Number = ");

ystem.out.println(+802);

/ Displaying a negative number

ystem.out.print("Second Number = ");ystem.out.println(-802);

uld produce:

mber = 802

umber = -802

, as many astill the same,

ng the + sign.

of two valuese2, you wouldadd more than

ns that Value1

a + c + b the

Computer Languages

C#

C++

Visual Basic


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n also get the

med as if you also add add

mple:

ing

8;


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)

uch numbers,

The simplestor the variablestrated in the


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is called the

you can writefollows:

dify the value

iler takes the

ue:


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t is modifyingd position the

On the other

t to increment

iable:


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eclare another

alue");

advantage is

e depends onm you will not

tly modify the

directly on thetever value a


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n combine the=. Here is an

alue");

second value.e the variable

dded to itself,

itself 4 times,

n it comes to

apply to the


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_highlighting

8;

;

OfDresses;

resses;

-/-");


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t to the same

ple:


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on assignment

value to the

t is essentially

the same as c


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n section, the

g

resses;


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ts);

;

1 from a value

a value. This


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is done using

ft or the rightor, the above

t the variables is illustrated


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erator on the

om a variable,

or. Here is an

alue");


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en you cut an

ng pieces, you

e in 4 parts.The division is

Make sure that


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OfDresses;

alDresses;

ts);

;


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e result to the

ple:

an example of


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u type an odd

get the valueotball (soccer)o start. If the

pressing Shift

n");

and assign the

.\n");


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und remainder

mple:

.\n");

ata in memory

presented onlyf changing the

not just abouturrent position

r is decimal or

ou will hardlyular basis. The

that we were

erse it to 0. If provides the

to binary is


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xample:

it. To support

to binary first.

6 converted to

Based on the


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on, use the &

variable. Here

or consists of


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tion, the Java

rted to binary

305 converted

101. Based on


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riable. Here is

wise exclusion,


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number 618

to binary iss follows:

variable itself.


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mple:

one ore more

ry equivalent.

e represented

eft, depending

bit to the leftosition y. You

s a value of 0.

ically perform


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xample:

itself. Here is


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