p04 - arithmetic operators 1.pdf

7/30/2019 P04 - Arithmetic Operators 1.pdf

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Computer Studies 2013 Syllabus

Mr. A. Gatt Page 1 of 5

Arithmetic Operators (04)

Basic calculations, assignments, unary, type conversion and type casting.

Introduction

A very good idea is to plan the program before start coding it in Java. There are two ways of coding a

program; pseudo-code or flowcharts. Pseudo-code use English like statements to plot the program whilst

flowcharts use graphical symbols. The following program could have been planned using either method as

shown below.

Java Program

class VariablesExample {

public static void main (String args[]){

//variables are declared are assigned

int N1 = 50;

int N2 = 13;

int tot;

//the total of variables N1 and N2

//is stored in tot

tot = N1 + N2;

//Finally, we can show the result

System.out.println(tot);

}

}


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Pseudo Code Flowchart

1. Start

2. Store 50 in N1.

3. Store 13 in N2.

4. Add N1 to N2 and store result in tot.

5. Display the value in tot.

6. Stop

As you can see from the flowchart there are different symbols which can be used as shown in the next

table. However, we will see them in more detail later on.

Symbol Name Use

Terminator Starts and ends a program.

Process Processing is anything done by the program which

doesnt require input or output, such as calculations and

variable declaration and assignments.

Decision Whenever a comparison must be done, the decision

symbol must be used and it must have two outputs

which are YES or NO.

Method If the program calls for a method, this symbol must be

used.

Start

N1 = 50

N2 = 13

tot = N1 + N2

Display tot

End


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Connector If a shape has more than one input, group them in a

connector beforehand.

Off-Page Connector If the flowchart does not fit on a single page it must be

continued on a different page using an off-page

connector.

Input / Output Whenever user input is required or something is

outputted this symbol must be used.

Arithmetic Operators

The basic arithmetic operators are + (addition), - (subtraction), / (division), * (multiplication) and %

(remainder or modulus). These are called binary operators because they involve two variables. Then there

are the unary operators which require only one variable. All of these operators can be seen in the next

table.

Operator Equivalent Operation Type

+ Addition

Binary

- Subtraction

* Multiplication

/ Division

% Remainder

++ x =x + 1 Increment (add 1)

Unary

-- x =x 1 Decrement (subtract 1)

+= x = x + y Add y to x

-= x = x y Subtract y from x

*= x =x * y Multiply x by y

/= x = x /y Divide x by y

%= x =x % y Divide x by y and get the remainder


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So there are various ways of writing the same arithmetic statement. The following table illustrates the

difference.

Operation A

is the same as

Operation B

x = x + 1 x++

x = x 1 x--

x =x + 8 x+=8

x = x 90 x-=90

x = x * 8 x*=8

x = x / 12 x/=12

Also keep in mind the precedence of operators; this means that if various operators are combined in the

same formula, they are worked out in the following manner:

1. Multiplication2. Division3. Remainder4. Addition5. Subtraction

So if we have:

result = 10 + 4 * 3 / 2;

It is worked out as follows:

10 + 4 * 3 / 2

10 + 12 / 2

10 + 6

16

However, brackets can be used which override precedence. So (10+4) * 3 / 2 will be worked out as:(10 + 4) * 3 / 2

(14) * 3 / 2

42 / 2

21

And as you can see its a totally different result.


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Activities

1. Draw a simple flowchart for the following program.

class averageTwo {

public static void main (String args[]) {

int n1 = 56;

int n2 = 12;

float avg = (n1 + n2) / 2;

System.out.println(Average is +avg);

}

}

2. What is the value of x in the following calculations?a. X = 5%3;b. X = 4 * 6 + (3 9);c. X += 6;

3. Write a program that stores your year of birth in a variable. Then use a calculation to show youractual age.

4. Write a program that shows the result of four calculations (+, -, / and *) of two numbers. The resultsmust be in the following format.

Two Numbers are 5 and 6

Addition : 11

Subtraction : -1

Multiplication : 30

Division : 0.833

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p04 - arithmetic operators 1.pdf

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