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| − | || ''Time'''
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| − | || '''Narration'''
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| − | | 00:02
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| − | | Welcome to the spoken tutorial on''' While Loop '''in java'''.'''
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| − | | 00:06
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| − | | In this tutorial, you will learn '''About the while loop.'''
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| − | '''How To use it.'''
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| − | | 00:12
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| − | | For this tutorial we are using
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| − | '''Ubuntu 11.10''',
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| − | '''JDK 1.6''' and
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| − | '''Eclipse 3.7'''
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| − | | 00:21
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| − | | To follow this tutorial, you must have knowledge of '''relational operators in Java'''
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| − | | 00:26
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| − | | If not, for relevant tutorials please visit our website as shown. [http://spoken-tutorial.org/ http][http://spoken-tutorial.org/ ://][http://spoken-tutorial.org/ spoken][http://spoken-tutorial.org/ -][http://spoken-tutorial.org/ tutorial][http://spoken-tutorial.org/ .][http://spoken-tutorial.org/ org]
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| − | | 00:36
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| − | | Here is the structure of a while loop.
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| − | | It has two parts.
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| − | | 00:41
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| − | | One is the '''loop running condition''' and the second is the '''loop variable.'''
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| − | | 00:48
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| − | | Let us now look at an example. Switch to Eclipse
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| − | | 00:55
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| − | | Here We have the eclipse IDE and the skeleton required for rest of the code
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| − | | 01:00
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| − | | I have created a class WhileDemo and added the main method to it.
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| − | | 01:05
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| − | | | We shall print numbers from 1 to 10 using a while loop. Type '''''int n = 1'' '''''
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| − | | 01:15
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| − | | This variable n is going to be our loop variable
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| − | | 01:21
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| − | | type '''''while ''''in ''parenthesis '''n''' less than or equal to'' '''''10''''' open and close braces
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| − | | 01:33
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| − | | This condition is called looping running condition.
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| − | | 01:37
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| − | | It means the loop will run as long as this condition is true.
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| − | | 01:42
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| − | | In our case, it will run as long as the value of '''n''' is less than or equal to 10.
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| − | | 01:47
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| − | | And it will stop only when the value of '''n''' become greater than 10.
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| − | | 01:53
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| − | | Inside the loop, we shall print the value of '''n'''
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| − | | '''System.out.println(n);''' and then increment '''n = n + 1;'''
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| − | | 02:12
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| − | | This way, first 1 is printed and then the value of n becomes 2.
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| − | | Then the loop condition is checked.
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| − | | Since it is true. 2 is printed and n becomes 3.
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| − | | 02:25
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| − | | And so on loop progresses untill 10 is printed after that n becomes 11 and the condition is not true and the loop will stop
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| − | | 02:37
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| − | | So Let us see the code in action.
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| − | | Save and run.
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| − | | 02:47
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| − | | As we can see, the numbers from 1 to 10 are printed.
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| − | | 02:52
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| − | | Now we shall print numbers from '''50''' to '''40'''
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| − | | 02:58
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| − | | So We start with 50. ''' Change n = 1 to n = 50'''
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| − | | 03:03
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| − | | And We go till 40.
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| − | | 03:05
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| − | | In other words as long as n ''is greater than or equal to ''40. So change the condition to n '' greater than or equal to ''40.
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| − | | 03:16
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| − | | And since we are looping from a bigger number to a smaller number, we have decrement the loop variable.
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| − | | 03:22
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| − | | So Change '''n=n + 1''' to '''n=n - 1'''
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| − | | 03:27
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| − | | Save and run. As we can see, the the numbers 50 to 40 have been printed
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| − | | 03:42
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| − | | Now we shall print the first 10 multiples of 7.
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| − | | To do that, we start with 7
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| − | | So change '''n = 50''' to '''n = 7'''and then end with 70.
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| − | | 03:57
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| − | | Change the condition to n''' ''less than equal to '''''70'''
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| − | | This way, we make sure the loop stops at 70.
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| − | | To get the multiples, we shall increment the loop variable by 7.
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| − | | 04:12
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| − | | So, change ''' n=n - 1''' to '''n=n + 7'''
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| − | | 04:18
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| − | | This way first 7 is printed and then n becomes 14, 14 is printed and so on untill 70. Save and run
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| − | | 04:33
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| − | | | As we can see, the first 10 multiples of 7 are printed.
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| − | | 04:43
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| − | | We can also use a while loop to get the sum of digits of a number.
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| − | | 04:47
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| − | | Let us see how to do so.
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| − | | 04:49
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| − | | First clear the main method.
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| − | | 04:54
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| − | | int '''n''' ''equal to'' '''13876'''. This is the number
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| − | | 05:02
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| − | | Then '''int dSum '''''equal to'' '''0'''The variable dsum with symbolic for digit sum will contain the sum of digits
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| − | | 05:18
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| − | | Type while, n greater than 0 open close parenthesis
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| − | | 05:27
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| − | | The reason for using this condition will be evident in a while.
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| − | | 05:32
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| − | | To get the sum of digits, we must first get the digits.
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| − | | 05:36
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| − | | To do that we use modulo operator.
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| − | | 05:40
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| − | | Type '''dSum = dSum + (n % 10)''' So we get the unit digit and add it to dsum
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| − | | 05:5
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| − | |After that we remove the digit by dividing by 10. n = n / 10
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| − | | 06:08
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| − | | So when the loop is run for the first time, '''dSum '''will be 6 and n will be 1387.
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| − | | 06:15
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| − | | And when the loop is run for the the second time, '''dSum''' will be sum of 7 and 6 which is 13, and '''n''' will become 138.
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| − | | 06:22
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| − | | So on, as the loop progresses, the digits will be removed from '''n''' and finally
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| − | | 06:28
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| − | | '''n''' become zero.After that the condition n greater than 0 will be false and the loop will stop
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| − | | 06:36
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| − | | So let us now add a print statement
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| − | | '''System.out.println(dSum)'''
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| − | | Let us see the code and action. Save and run
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| − | | 06:59
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| − | | As we can see the sum of digit which is 25 has been printed
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| − | | 07:06
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| − | | This way, a while loop, which is one of the most fundamental constructs in programming, can be used.
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| − | | 07:16
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| − | | This brings us to the end of the tutorial.
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| − | | 07:20
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| − | | In this tutorial we have learnt
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| − | * About while loop
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| − | * how to use it
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| − | |07:26
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| − | | As an assignment for this tutorial solve the following problem.
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| − | | 07:29
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| − | | Given a number, compute its reverse by using a while loop. Example: 19435 => 53491
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| − | |07:37
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| − | |To know more about the '''Spoken Tutorial''' project, watch the video available at the following link, that summarizes the Spoken Tutorial project
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| − | | 07:45
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| − | | If you do not have good bandwidth, you can download and watch it.
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| − | | 07:50
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| − | | The Spoken Tutorial Project Team, Conducts workshops using spoken tutorials, Gives certificates for those who pass an online test
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| − | | 07:57
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| − | | For more details, please write to '''contact AT spoken HYPHEN tutorial DOT org.'''
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| − | | 08:03
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| − | | '''Spoken Tutorial '''Project is a part of the '''Talk to a Teacher''' project.
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| − | | 08:07
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| − | | It is supported by the '''National Mission on Education through ICT, MHRD, Government of India.
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| − | | 08:12
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| − | | '''More information on this Mission is available at the following link
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| − | | 08:17
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| − | | This tutorial has been contributed by '''TalentSprint'''. Thanks for joining.
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| − | |}
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