Java/C2/whileloop/Englishtimed
From Script  SpokenTutorial
Time'  Narration 
00:02  Welcome to the spoken tutorial on While Loop in java. 
00:06  In this tutorial, you will learn About the while loop.
How To use it. 
00:12  For this tutorial we are using
Ubuntu 11.10, JDK 1.6 and Eclipse 3.7 
00:21  To follow this tutorial, you must have knowledge of relational operators in Java

00:26  If not, for relevant tutorials please visit our website as shown. http://spokentutorial.org 
00:36  Here is the structure of a while loop. 
00:39  It has two parts. 
00:41  One is the loop running condition and the second is the loop variable.

00:48  Let us now look at an example. Switch to Eclipse 
00:55  Here We have the eclipse IDE and the skeleton required for rest of the code

01:00  I have created a class WhileDemo and added the main method to it. 
01:05  We shall print numbers from 1 to 10 using a while loop. Type int n = 1

01:15  This variable n is going to be our loop variable 
01:21  type while 'in parenthesis n less than or equal to 10 open and close braces 
01:33  This condition is called looping running condition.

01:37  It means the loop will run as long as this condition is true.

01:42  In our case, it will run as long as the value of n is less than or equal to 10.

01:47  And it will stop only when the value of n become greater than 10. 
01:53  Inside the loop, we shall print the value of n 
01:58  System.out.println(n); and then increment n = n + 1;

02:12  This way, first 1 is printed and then the value of n becomes 2. 
02:18  Then the loop condition is checked.

02:21  Since it is true. 2 is printed and n becomes 3. 
02:25  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

02:37  So Let us see the code in action. 
02:39  Save and run. 
02:47  As we can see, the numbers from 1 to 10 are printed.

02:52  Now we shall print numbers from 50 to 40 
02:58  So We start with 50. Change n = 1 to n = 50 
03:03  And We go till 40.

03:05  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.

03:16  And since we are looping from a bigger number to a smaller number, we have decrement the loop variable.

03:22  So Change n=n + 1 to n=n  1

03:27  Save and run. As we can see, the the numbers 50 to 40 have been printed 
03:42  Now we shall print the first 10 multiples of 7. 
03:48  To do that, we start with 7

03:50  So change n = 50 to n = 7and then end with 70.

03:57  Change the condition to n less than equal to 70

04:03  This way, we make sure the loop stops at 70. 
04:07  To get the multiples, we shall increment the loop variable by 7.

04:12  So, change n=n  1 to n=n + 7

04:18  This way first 7 is printed and then n becomes 14, 14 is printed and so on untill 70. Save and run 
04:33  As we can see, the first 10 multiples of 7 are printed.

04:43  We can also use a while loop to get the sum of digits of a number.

04:47  Let us see how to do so. 
04:49  First clear the main method.

04:54  int n equal to 13876. This is the number 
05:02  Then int dSum equal to 0The variable dsum with symbolic for digit sum will contain the sum of digits

05:18  Type while, n greater than 0 open close parenthesis

05:27  The reason for using this condition will be evident in a while. 
05:32  To get the sum of digits, we must first get the digits. 
05:36  To do that we use modulo operator.

05:40  Type dSum = dSum + (n % 10) So we get the unit digit and add it to dsum 
05:52  After that we remove the digit by dividing by 10. n = n / 10 
06:08  So when the loop is run for the first time, dSum will be 6 and n will be 1387. 
06:15  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.

06:22  So on, as the loop progresses, the digits will be removed from n and finally 
06:28  n become zero.After that the condition n greater than 0 will be false and the loop will stop 
06:36  So let us now add a print statement 
06:42  System.out.println(dSum) 
06:51  Let us see the code and action. Save and run 
06:59  As we can see the sum of digit which is 25 has been printed 
07:06  This way, a while loop, which is one of the most fundamental constructs in programming, can be used. 
07:16  This brings us to the end of the tutorial.

07:20  In this tutorial we have learnt

07:26  As an assignment for this tutorial solve the following problem.

07:29  Given a number, compute its reverse by using a while loop. Example: 19435 => 53491 
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08:17  This tutorial has been contributed by TalentSprint. Thanks for joining.
