Chandrika: Created page with '{| border=1 !Time !Narration |- |00:00 |Welcome again! In this tutorial, we will learn the DO-WHILE loop. |- |00:04 |Its also called the DO-WHILE statement. You can choose to …'

2012-11-29T06:35:48Z

Created page with '{| border=1 !Time !Narration |- |00:00 |Welcome again! In this tutorial, we will learn the DO-WHILE loop. |- |00:04 |Its also called the DO-WHILE statement. You can choose to …'

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{| border=1
!Time
!Narration
|-
|00:00
|Welcome again! In this tutorial, we will learn the DO-WHILE loop.
|-
|00:04
|Its also called the DO-WHILE statement. You can choose to call it a loop or a statement.
|-
|00:11
|The base is similar to the WHILE loop, although the condition is checked at the END of the loop as opposed to the START.
|-
|00:20
|We have DO, our block with the curly brackets, and WHILE at the end. Then a condition in here. So this is the condition.
|-
|00:29
|Now I'm going to type a little program - I want the numbers to increment each time and echo on each line as I've done in my WHILE loop.
|-
|00:44
|Now the condition - when the number reaches 10, I want a variable called name, to be changed to another name in which the loop will stop.
|-
|00:59
|I'll type num = 1 to start with.
|-
|01:04
|Then I'll type my name is Alex.
|-
|01:09
|The condition of the loop I want is - while the name = Alex.
|-
|01:17
|As long as the name=Alex this will loop. So somewhere we need to say on a specific condition - change the name to Billy and then the loop won't continue any more because the name is not equal to Alex.
|-
|01:31
|Now, we will include an IF statement inside the DO loop. Remember you can put
* IF statements inside IF statements
* IF statements inside loops
* loops inside loops
and there's really no limit to what you do. As long as your code works and flows properly and doesn't produce infinite values, you will be fine.
|-
|01:52
|Now what we type is DO.
|-
|01:55
|Firstly, echo out the value of the number.
|-
|01:58
|You can concatenate that with a brief HTML code to break the line.
|-
|02:03
|Here I type num++ which is the same as num +1
|-
|02:14
|Then my IF statement - If num is greater than or equal to 10 then no echo.
|-
|02:26
|I want to change the name to Billy.
|-
|02:34
|Let me recap. Remember, I'm not using curly brackets here because I have one line of code that needs to be executed in the block after the IF statement
|-
|02:43
|Therefore I just need one line code because it looks neat.
|-
|02:50
|So, let me recap what I've done. I've got the number set to 1.
|-
|02:53
|This is my number variable, this can increment and can be echoed out to the user.
|-
|02:56
|I've got my name set to Alex.
|-
|03:00
|We start our DO.
|-
|03:02
|The name is still Alex.
|-
|03:04
|There's no condition so this will run regardless of anything
|-
|03;07
|So we echo out the number which is 1
|-
|03:09
|We increment it by 1 which will equal 2
|-
|03:12
|Now, we'll say if the number which is currently 2 is bigger than or equal to 10, (which it isn't) then continue through this
|-
|03:26
|It isn't. So skip this. It'll go on to say name = Alex. And then go back to the top.
|-
|03:33
|This will still be 2.That means the loop's stuck at that block of code.
|-
|03:41
|It'll echo out 2
|-
|03:43
|It'll add one and say 3
|-
|03:46
|And then it'll say, is 3 bigger than or equal to 10.
|-
|03:51
|Now, it's not.
|-
|03:52
|So, the name is not changed to Billy instead it'll carry on with the rest of our code.
|-
|03:56
|The name's still Alex
|-
|03:58
|So, the loop continues on. In this case it will go on until it reaches 10, but 9 will be echoed out to the user
|-
|04:07
|Now num will become 10
|-
|04:09
|The IF condition will be True.
|-
|04:11
|The name would be set to Billy and in the while condition it doesn't equal Alex.So the WHILE loop will stop and the code down here will continue.
|-
|04:28
|So lets execute this code. Do our loop. Click on that.
|-
|04:31
|OK, we've got 1 2 3 all the way up to 9.
|-
|04:35
|Obviously, our condition has been met. Our name has changed to Billy. Our name doesn't equal Alex anymore.
|-
|04:41
|So, our loop here has stopped.
|-
|04:44
|Now change the IF to 11 or you can change num to 0
|-
|04:50
|Now this won't work and you'll see why
|-
|04:54
|We've got 0 to 9
|-
|04:57
|The reason being is your starting number
|-
|05:02
|What this will do is, like I said before, it'll echo out the current number, then change it to an increment of 1 and then it'll compare it in the IF statement.
|-
|05:11
|So, you're comparing what you can't see.
|-
|05:13
|If you change this to 11, you'll compare it to 11, then change it to Billy and then it'll end the loop.
|-
|05:20
|We never see the value of 11, it's only an inside comparison.
|-
|05:26
|If we refresh this, we can see there's 1 to 10 now.
|-
|05:30
|That is basically the DO-WHILE loop. Even though they are pretty similar,the Do-WHILE loop is more useful than the WHILE loop when you run into a programming sort of logic. It may be more useful in some cases.
|-
|05:44
|So, practice this, try and enter some values. Also, try to recreate the program I've just created.
|-
|05:50
|There will be more tutorials on loops shortly So keep watching.
|-
|05:56
|This is Anoushka dubbing for the Spoken Tutorial Project.

PHP-and-MySQL/C2/Loops-Do-While-Statement/English - Revision history

Chandrika: Created page with '{| border=1 !Time !Narration |- |00:00 |Welcome again! In this tutorial, we will learn the DO-WHILE loop. |- |00:04 |Its also called the DO-WHILE statement. You can choose to …'