Difference between revisions of "Java/C2/while-loop/English-timed"
From Script | Spoken-Tutorial
Sandhya.np14 (Talk | contribs) |
PoojaMoolya (Talk | contribs) |
||
| (4 intermediate revisions by 3 users not shown) | |||
| Line 1: | Line 1: | ||
| − | |||
{| border=1 | {| border=1 | ||
|| '''Time''' | || '''Time''' | ||
| Line 7: | Line 6: | ||
|- | |- | ||
| 00:02 | | 00:02 | ||
| − | | Welcome to the spoken tutorial on ''' | + | | Welcome to the spoken tutorial on '''while loop''' in java. |
|- | |- | ||
| 00:06 | | 00:06 | ||
| − | | In this tutorial, you will learn: | + | | In this tutorial, you will learn: About the '''while loop''' and How to use it. |
| − | + | ||
| − | + | ||
|- | |- | ||
| 00:12 | | 00:12 | ||
| For this tutorial, we are using: | | For this tutorial, we are using: | ||
| − | '''Ubuntu 11.10''', | + | '''Ubuntu 11.10''', '''JDK 1.6''' and '''Eclipse 3.7'''. |
| − | '''JDK 1.6''' and | + | |
| − | '''Eclipse 3.7''' | + | |
|- | |- | ||
| 00:21 | | 00:21 | ||
| − | | To follow this tutorial, you must have knowledge of '''relational operators in Java'''. | + | | To follow this tutorial, you must have knowledge of '''relational operators''' in '''Java'''. |
|- | |- | ||
| Line 56: | Line 51: | ||
|- | |- | ||
| 01:05 | | 01:05 | ||
| − | | | + | | We shall print the numbers from '''1''' to '''10''' using a '''while loop'''. Type: '''int n = 1;'''. |
|- | |- | ||
| Line 68: | Line 63: | ||
|- | |- | ||
| 01:33 | | 01:33 | ||
| − | | This condition is called ''' | + | | This condition is called '''loop running condition'''. |
|- | |- | ||
| Line 88: | Line 83: | ||
|- | |- | ||
| 01:58 | | 01:58 | ||
| − | | '''System.out.println(n);''' and then increment '''n = n + 1;''' | + | | '''System.out.println(n);''' and then increment it '''n = n + 1;''' |
|- | |- | ||
| Line 120: | Line 115: | ||
|- | |- | ||
| 02:52 | | 02:52 | ||
| − | | Now we shall print numbers from '''50''' to '''40'''. | + | | Now, we shall print numbers from '''50''' to '''40'''. |
|- | |- | ||
| 02:58 | | 02:58 | ||
| − | | So, we start with 50. | + | | So, we start with 50. Change '''n = 1''' to '''n = 50'''. |
|- | |- | ||
| 03:03 | | 03:03 | ||
| − | | And We go till 40 | + | | And We go till 40, |
|- | |- | ||
| 03:05 | | 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. |
|- | |- | ||
| Line 144: | Line 139: | ||
|- | |- | ||
| 03:27 | | 03:27 | ||
| − | | '''Save''' and '''run'''. As we can see, the numbers 50 to 40 have been printed. | + | | '''Save''' and '''run'''. As we can see, the numbers from 50 to 40 have been printed. |
|- | |- | ||
| Line 156: | Line 151: | ||
|- | |- | ||
| 03:50 | | 03:50 | ||
| − | | So, change '''n = 50''' to '''n = 7''' and then end with 70. | + | | So, change '''n = 50''' to '''n = 7''' and then we end with 70. |
|- | |- | ||
| 03:57 | | 03:57 | ||
| − | | Change the condition to '''n''' less than equal to '''70'''. | + | | Change the condition to '''n''' less than or equal to '''70'''. |
|- | |- | ||
| 04:03 | | 04:03 | ||
| − | | This way, we make sure the '''loop''' stops at 70. | + | | This way, we make sure that the '''loop''' stops at 70. |
|- | |- | ||
| Line 172: | Line 167: | ||
|- | |- | ||
| 04:12 | | 04:12 | ||
| − | |So, change '''n=n-1''' to '''n= n+7''' | + | |So, change '''n=n-1''' to '''n= n+7;''' |
|- | |- | ||
| Line 196: | Line 191: | ||
|- | |- | ||
| 04:54 | | 04:54 | ||
| − | | '''int n''' equal to '''13876'''. This is the number. | + | | '''int n''' equal to '''13876;'''. This is the number. |
|- | |- | ||
| 05:02 | | 05:02 | ||
| − | | Then '''int dSum''' equal to '''0''' The variable '''dsum''' | + | | Then '''int dSum''' equal to '''0'''. The variable '''dsum''' which is symbolic for digit sum will contain the sum of digits. |
|- | |- | ||
| 05:18 | | 05:18 | ||
| − | | Type: '''while n''' greater than '''0''' open close | + | | Type: '''while n''' greater than '''0''' open close parentheses. |
|- | |- | ||
| Line 215: | Line 210: | ||
|- | |- | ||
| 05:36 | | 05:36 | ||
| − | | To do that, we use '''modulo operator'''. | + | | To do that, we use the '''modulo operator'''. |
|- | |- | ||
| 05:40 | | 05:40 | ||
| − | | Type: '''dSum = dSum + (n % 10)''' So, we get the unit digit and add it to '''dsum'''. | + | | Type: '''dSum = dSum + (n % 10)''' So, we get the unit's digit and add it to '''dsum'''. |
|- | |- | ||
| Line 227: | Line 222: | ||
|- | |- | ||
| 06:08 | | 06:08 | ||
| − | | So when the '''loop''' is '''run''' for the first time, '''dSum''' will be 6 and 'n' will | + | | So when the '''loop''' is '''run''' for the first time, '''dSum''' will be 6 and 'n' will become 1387. |
|- | |- | ||
| Line 235: | Line 230: | ||
|- | |- | ||
| 06:22 | | 06:22 | ||
| − | | | + | | And so on as the loop progresses, the digits will be removed from '''n''' and finally |
|- | |- | ||
| Line 250: | Line 245: | ||
|- | |- | ||
| 06:51 | | 06:51 | ||
| − | | Let us see the code | + | | Let us see the code in action. '''Save''' and '''run'''. |
|- | |- | ||
| 06:59 | | 06:59 | ||
| − | | As we can see, the sum of | + | | As we can see, the sum of digits which is 25 has been printed. |
|- | |- | ||
| 07:06 | | 07:06 | ||
| − | | This way | + | | This way a '''while loop''' which is one of the most fundamental '''constructs''' in programming can be used. |
|- | |- | ||
| Line 265: | Line 260: | ||
|- | |- | ||
| 07:20 | | 07:20 | ||
| − | | In this tutorial, we have | + | | In this tutorial, we have learned: About while loop.How to use it. |
| − | + | ||
| − | + | ||
|- | |- | ||
| Line 279: | Line 272: | ||
|- | |- | ||
|07:37 | |07:37 | ||
| − | |To know more about the Spoken Tutorial project, watch the video available at the following link | + | |To know more about the Spoken Tutorial project, watch the video available at the following link. It summarizes the Spoken Tutorial project. |
|- | |- | ||
| Line 287: | Line 280: | ||
|- | |- | ||
| 07:50 | | 07:50 | ||
| − | | The Spoken Tutorial Project Team: Conducts workshops using spoken tutorials. Gives certificates | + | | The Spoken Tutorial Project Team: Conducts workshops using spoken tutorials. Gives certificates to those who pass an online test. |
|- | |- | ||
| 07:57 | | 07:57 | ||
| − | | For more details, please write to '''contact | + | | For more details, please write to '''contact@spoken-tutorial DOT org.''' |
|- | |- | ||
Latest revision as of 11:02, 18 October 2017
| 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 and 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. [1] |
| 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 the 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 loop 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' becomes greater than 10. |
| 01:53 | Inside the loop, we shall print the value of 'n'. |
| 01:58 | System.out.println(n); and then increment it 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 until 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 decremented the loop variable. |
| 03:22 | So Change n=n+1 to n=n-1. |
| 03:27 | Save and run. As we can see, the numbers from 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 = 7 and then we end with 70. |
| 03:57 | Change the condition to n less than or equal to 70. |
| 04:03 | This way, we make sure that 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 until 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 0. The variable dsum which is symbolic for digit sum will contain the sum of digits. |
| 05:18 | Type: while n greater than 0 open close parentheses. |
| 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 the modulo operator. |
| 05:40 | Type: dSum = dSum + (n % 10) So, we get the unit's 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 become 1387. |
| 06:15 | And when the loop is run for the second time, dSum will be sum of 7 and 6 which is 13 and 'n' will become 138. |
| 06:22 | And so on as the loop progresses, the digits will be removed from n and finally |
| 06:28 | n becomes 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 in action. Save and run. |
| 06:59 | As we can see, the sum of digits 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 learned: 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 |
| 07:37 | To know more about the Spoken Tutorial project, watch the video available at the following link. It summarizes the Spoken Tutorial project. |
| 07:45 | If you do not have good bandwidth, you can download and watch it. |
| 07:50 | The Spoken Tutorial Project Team: Conducts workshops using spoken tutorials. Gives certificates to those who pass an online test. |
| 07:57 | For more details, please write to contact@spoken-tutorial DOT org. |
| 08:03 | Spoken Tutorial Project is a part of the Talk to a Teacher project. |
| 08:07 | It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
| 08:12 | More information on this mission is available at the following link. |
| 08:17 | This tutorial has been contributed by TalentSprint. Thanks for joining. |
