Difference between revisions of "Java/C2/do-while/English-timed"
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| − | + | | In this tutorial, you will learn about: | |
| − | + | '''do-while loop''' and | |
| − | + | '''how to use it''' | |
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| 00:12 | | 00:12 | ||
| For this tutorial, we are using: | | For this tutorial, we are using: | ||
| − | + | '''Ubuntu 11.10''' | |
| − | + | '''JDK 1.6''' and | |
| − | + | '''Eclipse 3.7''' | |
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| 02:37 | | 02:37 | ||
| − | + | | We see that the numbers from 1 to 10 are printed. | |
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| 04:15 | | 04:15 | ||
| − | + | | First clear the '''main method'''. | |
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|05:10 | |05:10 | ||
| − | + | | As long as '''x''' into '''x''' is less than '''n''', we keep incrementing the value of 'x'. | |
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Latest revision as of 19:27, 20 February 2017
| 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 |
| 07:56 | To know more about the Spoken Tutorial project, watch the video available at the following link. |
| 08:01 | It summarizes the spoken-tutorial project. If you do not have good bandwidth, you can download and watch it. |
| 08:06 | The Spoken Tutorial project team: |
| 08:10 | Conducts workshops using spoken tutorials, gives certificates to those who pass an online test. |
| 08:16 | For more details, please write to contact AT spoken HYPHEN tutorial DOT org. |
| 08:22 | The Spoken Tutorial project is a part of the Talk to a Teacher project. It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
| 08:32 | More information on this mission is available at the following link. |
| 08:36 | This tutorial has been contributed by TalentSprint. Thanks for joining. |
