COMPUTER PROGRAMMING (TMK 3102) LECTURE NOTES 8

8/9/2019 COMPUTER PROGRAMMING (TMK 3102) LECTURE NOTES 8

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TMK 3102-Chap 8: Control

Statement Loo

1

Chapt er 8: Contro l St a t em ent s (Loop)

Session Plan (Week 8):To understand:

Understand the various concepts of loop control

structure


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TMK 3102-Chap 8: ControlStatement Loo

2

In t roduct ion (rec a l l ) Program control specifies the order the

statements are executed in a program

Program execute statements insequence

How to by pass the sequencesselection statements

Or How to repeat the sequencesloop statements


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3

Why w e need l oop? (1)

Cons ider t he St a tem ent s :

I will do my

homework!!

Write a java program to print the following statement 100 times


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4


Cons ider t he St a tem ent s :

I will do my

homework!!

Write a java program to print the following statement 100 times

public static void main(String[] args){System.out.println(1. I will do my homework);..

System.out.println(100. I will do my homework);

}


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5


Can you

identify the

input and

output???

Write a java program for the

following problem:

Read 5 integer and display the

value of their summation.

Input : 5 integern1, n2, n3, n4, n5

Output: The summation ofn1, n2,n3, n4, n5

Input example: 2 3 4 5 6

Output example: 20


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Input n1

Input n2

Input n3

input n4

input n5

output sum

sum n1+n2+n3+n4+n5

start

end

..

..

.

n1 = in.nextInt();

n2 = in.nextInt();n3 = in.nextInt);

n4 = in.nextInt();

n5 = in.nextInt();

sum = n1+n2+n3+n4+n5

System.out.println(Sum=+sum);

6


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Input n1

Input n2

Input n3

input n4

input n5

output sum

sum n1+n2+n3+n4+n5

start

end

..

..

.

n1 = in.nextInt();

n2 = in.nextInt();n3 = in.nextInt);

n4 = in.nextInt();

n5 = in.nextInt();

sum = n1+n2+n3+n4+n5

System.out.println(Sum=+sum);

7

HOW if number ofinput is more than

1000?


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8

l oop s ta t ement s

Change the program flow by execute ablock of statements repeatedly

whileloop

forloop

do.whileloop Loop Flow Control : breakand continue


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while Loop

Syntaxes

while (condition)

statement;

or

while (condition) {statement1;statement2;statements;

}

condition false

true

Statement(s)


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while Loop Condition is tested first. Loop is controlled by condition One of statement must change the condition to

false to stop looping, otherwise infinite loop Use conditional operation as statement to

satisfied condition

conditionfalse

true

Statement(s)

count =0;while (count < 100){

System.out.println(welcome);

count++;

}

//example of infinite loop

count =0;

while (count < 100)

System.out.println(welcome);10


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w hi le Loop (c ount er cont ro l)

Example:

i=0;

while (i


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while Loop (sent ine l cont ro l )

number of loop is uncertain

int i=2, input = 0;

while (input != 1){

System.out.print(i x i=+i+x+i+=);i=i*i;

System.out.println(i);

System.out.print(press 1 to stop:);

input = in.nextInt();}

System.out.println(Program Finished);


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Self Test

How many times will the following loopexecute?

ctr = 0;

while (ctr == 5){

System.out.printf(ctr : %d,ctr);

ctr++;

}


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while Loop (c ase s t udy 1)

Write a java program that lets the userenter students grades. The program

then asked if user still has a grades ornot. When all grades data have beenentered, the program will calculate thegrade average and display it on the

screen.


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while Loop (c ase s t udy 2)

In January 2000, Ibrahim put RM25,000 ina retirement fund that paying 8.5 %interest per year. Now, he wants to know

how much money his fund will contain inyear 2020 and the interest made everyyear. He like to see this information in aform of table. Help him by writing a java

program to calculate and display therelated information as requested.


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for Loop

Condition is tested first

Loop is controlled by a counter

Syntaxes

for (initial value ; condition; update counter)statement;

OR

for (initial value ; condition; update counter) {

statement;

statement;

}


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for Loop f low

Initial value

condition

false

true

increase counter

Statement(s)

Syntax

for(initial value;condition;

increasecounter)Statement(s)


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for Loop f low

for (i=0; i


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for Loop f low 2

int sum=0;

int val = 0;

for (i=1; i


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Self Test

What is the value of i after execution:

num =0;for (i=0;i>10;i++){

num += i;

System.out.println(i + + num);

}


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Self Test

What is the output of the following javasegment:

num =0;

for (i=9;i>=0;i--) {

num = num + 10 * (i -1)

System.out.print(num + );

}

System.out.println();


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Self Test

Write a java program that used a forstatement to produce the Multiplication

Table for any number enter by user. Themultiplication for that number start withnumber 1 and end with number 12.


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do-w hi le Loop

Statements in the loop are executed first (atleast once, and condition is tested last

Loop is controlled by a condition or counter

Syntaxdo {

statement;

statement;

} while (condition);

statement;


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do-while Loop Ex am ple

int num=0; int sum=0;

num = in.nextInt();

do {

sum = sum + num% 10;num = num / 10;

} while (num > 0);

System.out.println(Sum of the digit : + sum);


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num = in.nextInt();do {

sum = sum + num% 10;

num = num / 10;

} while (num > 0);


num

sum

12867

0

sum = sum + num % 10

sum = 0 + 12867 %10

sum = 0 + 7

sum = 7

7

num = num /10

num = 12867 / 10

num = 1286

1286


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num = num / 10;

} while (num > 0);


num

sum


sum = 7 + 1286 %10

sum = 7 + 6

sum = 13

7

num = num /10

num = 1286 / 10

num = 128

1286

13

128


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num = num / 10;

} while (num > 0);


num

sum


sum = 13 + 128 %10

sum = 13 + 8

sum = 21

13

num = num /10

num = 128 / 10

num = 12

128

21

12



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num = num / 10;

} while (num > 0);


num

sum


sum = 23 + 1 %10

sum = 23 + 1

sum = 24

23

num = num /10

num = 1 / 10

num = 0

1

24

0


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num = num / 10;

} while (num > 0);


num

sum 29

1

24

0

Sum of the digit : 24


29


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Nested Loop

The body of a loop is again a loop. Describe as inner loop nested inside outer

loop

A loop within a loop

for(;;){

for(;;) {

}}

while(){

for(;;) {

}}

for(;;){

while()

{}

}


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Nest ed Loop (Ex am ple )

Draw a triangle of * by determine thesize of triangle first. Example; if size is 5,then the triangle is:

******

*********


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Nest ed Loop (Ex am ple )

//import section

import java.util.Scanner;

public class NestedLoopExample {

public static void main(String[] args) {

//declaration section

int i,j,input;

Scanner console = new Scanner(System.in);

//input sectionSystem.out.print("What is the size of the triangle:");

input = console.nextInt();

//process section

for(i=1;i


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Nested Loop (Ex am ple det a i ls )

//process section

for(i=1;i


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break Sta tement

(Recall) in switch break used to skip nextstatement

Used to exit early froma loop.

Can be placed within ifstatement of a loop.

If condition is meet,loop is exitedimmediately.

loopfalse

true

Statement(s)

if..

break

true

false


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break examp le

Add the integers from 1 to 20 in the order tosum until sum is equal or greater than 8.public class BreakExample {

public static void main(String[] args){int sum =0;int num;for(num =1;num < 20;num++) {

sum+=num;if (sum >= 8)

break;}System.out.println(Finish);

}}


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continue Sta tements

Used in while, for, and do...whilestructures.

When executed in a loop, the remainingstatements in the loop are skipped; proceedswith the next iteration of the loop.

When executed in a while/dowhilestructure, expression is evaluated immediatelyafter continue statement.

In a for structure, the update statement isexecuted after the continue statement; theloop condition then executes.


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continue example

Add all integers from 1 to 10 except the

number that can divide by 3.

37

l


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continue example



public class ContinueExample {public static void main(String[] args){

int sum =0;int num;for(num =1;num


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continue example



public class ContinueExample {public static void main(String[] args){

int sum =0;int num;for(num =1;num


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label refer to some location where loopstatement exist in java program by thespecial name.

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whileloop:// label

while( condition) {

forloop://label

for(i=0;i


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continue and break w i th labe l

import java.util.Scanner;

public class labelexample {

public static void main(String[] args) {

Scanner console = new Scanner(System.in);

whileloop:

while (true){forloop:

for(int i = 0; i < 100; i++) {

int c = console.nextInt();

if (c == 1)

continue whileloop;

else if ( c == 2)

break forloop;else

System.out.println(c);

}

System.out.println(">");

}

}

}


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Thank You

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COMPUTER PROGRAMMING (TMK 3102) LECTURE NOTES 8