Difference between revisions of "PHP-and-MySQL/C2/Loops-While-Statement/English-timed"
From Script | Spoken-Tutorial
| Line 1: | Line 1: | ||
{| border=1 | {| border=1 | ||
| − | + | |Time | |
| − | + | |Narration | |
|- | |- | ||
|00:00 | |00:00 | ||
Revision as of 11:15, 10 July 2014
| Time | Narration |
| 00:00 | Hello and welcome. I have decided to create seperate tutorials for each looping statement. |
| 00:07 | I want to keep it simple. This will be useful as a reference also if you need to refer to how a particular loop works. |
| 00:17 | In this tutorial, we will learn about the WHILE loop |
| 00:21 | A WHILE loop checks for a condition at the start at the loop and executes the code depending on whether this condition is True or not |
| 00:38 | for example I'll start my 'WHILE loop' here and this is the condition and this is my block. |
| 00:51 | I'll represent my block between curly brackets. |
| 00:56 | My condition is here. Now, in the 'IF statement', for example I used 1==1. |
| 01:04 | Now if I say 'test' or 'loop' here. |
| 01:07 | This is a loop here and then a break. Now what happens is as long as 1=1, it would create a loop |
| 01:17 | If I do something here, lets try this. |
| 01:22 | It would probably crash your browser because the loop would be repeated as long as 1=1 and for infinite no. of times, 1 will always equal 1. |
| 01:34 | So since the loop will always be repeated, your browser will crash. |
| 01:40 | Lets say while a variable, 'num' is smaller or equal to 10 and under echo i can say - 'num ++' |
| 01:57 | '++' is an arithmetical operator. And what it basically does is, it increases num by 1. It is the same as writing 'num =num +1' |
| 02:16 | So it takes num and says that it is equal to the value of num plus 1. |
| 02:23 | So this again is an arithmetical operator. What's going to happen is - |
| 02:29 | We are going to say 'num' lesser than or equal to '10', if yes then echo loop and then say add 1 on to the variable num |
| 02:41 | But what we should really do is create 'num = 1' at the moment. So loop once at 1. This will then equal 2 then 3 then 4 all the way up to 10 and then it will stop |
| 03:01 | After that the rest of the code below this will continue. |
| 03:06 | So we said this 1 and see what will we get. Okay we got a loop 1,2,3,4,5,6,7,8,9,10 times |
| 03:20 | Now to make it more fun I'll say loop 1 and I'll concatenate 'num' to the end of that |
| 03:27 | In fact let's make it simpler and say 'num' inside - it will make it much easier to read |
| 03:37 | Okay I'll say loop 1 and add 1 and then I'll say loop 2 and I'll add another 1; that's loop 3 add another 1 up to 10. |
| 03:49 | Lets open this up. Refresh it. There you go. You got loop 1,2,3 all the way up to 10 as you can see |
| 03:58 | Lets change this value here to 100. Refresh that. You can see it has gone to hundred. The bigger the number, the longer it will take to loop |
| 04:08 | Let's take 6000. Let's refresh that. It's going to take a while. There you go - up to 6000. So it's very efficient in this way |
| 04:20 | You can try combining this with an 'array' to create a program that echoes out of the alphabet inside the 'array' |
| 04:27 | You can use loops to echo out every single value of an array |
| 04:32 | Just give it a go. I will probably do this in one my tutorial - not in the basics section though |
| 04:40 | However, this is the basics structure. What I also recommend you to do is create a variable here called 'max' and put your maximum value here |
| 04:53 | This will do exactly the same thing. It's just a lot more easy to read and you can declare all this here and this would be a reference to it |
| 05:03 | If you have more than 1 loop. I prefer it for readability and flexibility for my program. Okay so that's a WHILE loop. Let me summarise. It checks the condition of the start |
| 05:17 | If the condition is True. it would execute this block of code and you can do things like 'echo alpha' |
| 05:24 | Your variable is being incremented. Make sure that you do increment your variable otherwise it will loop for infinity. |
| 05:32 | Thanks for watching. This is Sidharth for the Spoken Tutorial Project, signing off. Goodbye. |
