PHP-and-MySQL/C2/Loops-While-Statement /English
From Script | Spoken-Tutorial
| Time | Narration |
|---|---|
| 0:00 | Hello and welcome. I have decided to create seperate tutorials for each looping statement. |
| 0:07 | 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. |
| 0:22 | In this tutorial, we will learn about the WHILE loop |
| 0:25 | 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 |
| 0:35 | for example I'll start my 'WHILE loop' here and this is the condition and this is my block |
| 0:44 | I'll represent my block between curly brackets |
| 0:52 | My condition is here. Now, in the 'IF statement', for example I used 1=1. |
| 1:02 | Now if I say 'test' or 'loop' here. |
| 1:08 | There is a loop here and then a break. Now what happens is as long as 1=1, it would create a loop |
| 1:14 | If I do something here, lets try this. |
| 1:19 | 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 |
| 1:29 | So since the loop will always be repeated, your browser will crash |
| 1:33 | Lets say while a variable, 'num' is smaller or equal to 10 and under echo i can say - 'num ++' |
| 1:57 | '++' is an arithmetical operator. And what it basically does is, it increases num by 1. It is the same as writing 'num =num +1' |
| 2:16 | So it takes num and says that it is equal to the value of num plus 1. |
| 2:22 | So this again is an arithmetical operator. What's going to happen is - |
| 2:29 | 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 |
| 2:46 | 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 |
| 3:02 | After that the rest of the code below this will continue |
| 3:06 | So we said this 1 and see what will we get. Okay we got a loop 1,2,3,4,5,6,7,8,10 times |
| 3:20 | Now to make it more fun I'll say loop 1 and I'll concatenate 'num' to the end of that |
| 3:29 | In fact let's make it simpler and say 'num' inside - it will make it easier to read |
| 3:37 | 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. |
| 3:49 | 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 |
| 3:57 | 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 |
| 4:09 | 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 |
| 4:20 | You can try combining this with an 'array' to create a program that echoes out of the alphabet inside the 'array' |
| 4:33 | You can use loops to echo out every single value of an array |
| 4:36 | Just give it a go. I will probably do this in one my tutorial - not in the basics section though |
| 4:45 | 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 |
| 4:54 | It 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 |
| 5:02 | 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 |
| 5:15 | If that condition is True. it would execute this block of code and you can do things like 'echo alpha' |
| 5:21 | Your variable is being incremented. Make sure that you do increment your variable otherwise it will loop for infinity. |
| 5:31 | Thanks for watching. This is Sidharth for the Spoken Tutorial Project, signing off. Goodbye. |
