Java/C2/do-while/English-timed

Time	Narration
00:01	Welcome to the spoken tutorial on do-while Loop in java.
00:06	In this tutorial, you will learn about: do-while loop and how to use it
00:12	For this tutorial, we are using: Ubuntu 11.10 JDK 1.6 and Eclipse 3.7
00:20	To follow this tutorial, you must have knowledge of while loop in java.
00:25	If not, for relevant tutorials, please visit our website as shown.
00:32	Here is the structure for do-while loop.
00:37	Notice that it is similar to a while loop.
00:40	It has two parts.
00:42	First is the loop running condition. And the second is the loop variable.
00:51	The only difference is that the condition is written after the do block.
00:58	And so, the condition is checked after the execution of the statements inside the do block.
01:05	Now, let us see an example.
01:07	Switch to eclipse.
01:11	Here we have Eclipse IDE and the skeleton required for the rest of the code.
01:17	We have created a class DoWhileDemo and added the main method to it.
01:22	We are going to print the numbers from 1 to 10 using a do-while loop.
01:27	Type:
01:29	int n equal to 1;.
01:32	'n' is going to be the loop variable.
01:36	Then type: do
01:40	open and close braces
01:44	Inside the braces System.out.println(n);
01:55	We shall print the value of 'n' and then increment it. n equal to n plus 1;
02:05	And we do this as long as
02:08	n is less than or equal to 10.
02:10	So, outside the braces, type: while in parentheses n less than or equal to 10.
02:20	and close the do-while using a semicolon.
02:25	Let us see the code in action.
02:28	Save and Run.
02:37	We see that the numbers from 1 to 10 are printed.
02:42	Now, let us understand how the code is executed.
02:47	First, the value 1 is printed and then 'n' becomes 2.
02:52	And then, the condition is checked.
02:55	since it is true, again 2 is printed and 'n' becomes 3.
03:00	And so on till all the 10 numbers are printed and the value of 'n' becomes 11.
03:06	When n = 11, the condition fails and the loop stops.
03:11	Now, let us print numbers from 50 to 40 in decreasing order.
03:17	So, we start with 50.
03:19	So, change n = 1 to n = 50.
03:23	Since we are looping from a bigger number to a smaller number, we decrement the loop variable.
03:29	So, change n = n + 1 to n = n - 1.
03:34	We loop as long as 'n' is greater than or equal to 40.
03:40	So, change the condition to n >= 40.
03:48	Let us look at the output.
03:50	Save and Run.
03:57	As we can see, the numbers from 50 to 40 are printed.
04:02	Now let us try a different logic using the do-while loop.
04:10	Given a number, we shall find out if it is a perfect square or not.
04:15	First clear the main method.
04:19	Then, type int n = 25;
04:25	We shall see if the value in 'n' is a perfect square or not.
04:32	Then type int x = 0;
04:37	We shall use 'x' to store the square root of the number if it is a perfect square.
04:44	Then type do
04:46	Open and close braces.
04:49	Inside the braces, x equal to x plus 1;
04:55	and outside the braces
04:58	while in parentheses x into x is less than n
05:06	And close the do-while using a semi-colon.
05:10	As long as x into x is less than n, we keep incrementing the value of 'x'.
05:16	So, when the loop stops the reverse of this condition will be true.
05:22	Which means, either 'x into x' must be equal to 'n'
05:26	or it must be greater than 'n'.
05:28	If x into x is equal to n, the number is a perfect square.
05:32	If it is not equal to 'n', the number is not a perfect square.
05:37	So finally, we print the condition.
05:47	System.out.println (x * x == n);
05:55	Let us see the code in action.
05:59	Save and Run. As we can see, the output is true.
06:07	Let us try with another perfect square.
06:10	Change n = 25 to n = 49.
06:15	Save and Run.
06:20	We see that we get a true again .
06:23	Let us try with a number which is not a perfect square.
06:26	Change 49 to 23. Save and Run and
06:34	we get a false as expected.
06:37	Now, let us see what happens when the value of 'n' is 0.
06:42	Change n = 23 to n = 0. Since 0 is not a natural number, we must get a false.
06:52	Let us run the code.
06:54	Save and Run.
07:00	We see that we get false as expected.
07:05	This happens because even before the condition
07:08	x into x is less than n is checked, the value of 'x' is incremented and it becomes 1.
07:16	The loop condition fails and the loop does not run.
07:20	This way, by using a do-while loop, we make sure that 0 is not considered as a perfect square.
07:26	This way, a do-while loop is used for solving a range of problems.
07:31	Specially, when the loop must run at least once.
07:37	This brings us to the end of the tutorial.
07:40	In this tutorial, we have learnt about
07:42	the do-while loop and how to use it.
07:46	As an assignment for this tutorial, solve the following problem.
07:50	Given a binary number, find out its decimal equivalent. Example: 11010 => 26
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08:36	This tutorial has been contributed by TalentSprint. Thanks for joining.

Contributors and Content Editors

Gaurav, PoojaMoolya, Sandhya.np14, Sneha