Java/C2/while-loop/English-timed

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://spoken-tutorial.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
05:5	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 About while loop how to use it
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.

Contributors and Content Editors

Gaurav, PoojaMoolya, Pratik kamble, Sandhya.np14, Sneha