1 00:00:00 --> 00:00:06 Hello and welcome. I have decided to create seperate tutorials for each looping statement. 2 00:00:07 --> 00:00:16 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. 3 00:00:17 --> 00:00:20 In this tutorial, we will learn about the WHILE loop 4 00:00:21 --> 00:00:37 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 5 00:00:38 --> 00:00:50 for example I'll start my 'WHILE loop' here and this is the condition and this is my block. 6 00:00:51 --> 00:00:55 I'll represent my block between curly brackets. 7 00:00:56 --> 00:01:03 My condition is here. Now, in the 'IF statement', for example I used 1==1. 8 00:01:04 --> 00:01:06 Now if I say 'test' or 'loop' here. 9 00:01:07 --> 00:01:16 This is a loop here and then a break. Now what happens is as long as 1=1, it would create a loop 10 00:01:17 --> 00:01:21 If I do something here, lets try this. 11 00:01:22 --> 00:01:33 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. 12 00:01:34 --> 00:01:39 So since the loop will always be repeated, your browser will crash. 13 00:01:40 --> 00:01:56 Lets say while a variable, 'num' is smaller or equal to 10 and under echo i can say - 'num ++' 14 00:01:57 --> 00:02:15 '++' is an arithmetical operator. And what it basically does is, it increases num by 1. It is the same as writing 'num =num +1' 15 00:02:16 --> 00:02:22 So it takes num and says that it is equal to the value of num plus 1. 16 00:02:23 --> 00:02:28 So this again is an arithmetical operator. What's going to happen is - 17 00:02:29 --> 00:02:40 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 18 00:02:41 --> 00:03:00 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 19 00:03:01 --> 00:03:05 After that the rest of the code below this will continue. 20 00:03:06 --> 00:03:19 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 21 00:03:20 --> 00:03:26 Now to make it more fun I'll say loop 1 and I'll concatenate 'num' to the end of that 22 00:03:27 --> 00:03:36 In fact let's make it simpler and say 'num' inside - it will make it much easier to read 23 00:03:37 --> 00:03:48 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. 24 00:03:49 --> 00:03:57 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 25 00:03:58 --> 00:04:07 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 26 00:04:08 --> 00:04:19 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 27 00:04:20 --> 00:04:26 You can try combining this with an 'array' to create a program that echoes out of the alphabet inside the 'array' 28 00:04:27 --> 00:04:31 You can use loops to echo out every single value of an array 29 00:04:32 --> 00:04:39 Just give it a go. I will probably do this in one my tutorial - not in the basics section though 30 00:04:40 --> 00:04:52 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 31 00:04:53 --> 00:05:02 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 32 00:05:03 --> 00:05:16 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 33 00:05:17 --> 00:05:23 If the condition is True. it would execute this block of code and you can do things like 'echo alpha' 34 00:05:24 --> 00:05:31 Your variable is being incremented. Make sure that you do increment your variable otherwise it will loop for infinity. 35 00:05:32 --> 00:05:37 Thanks for watching. This is Sidharth for the Spoken Tutorial Project, signing off. Goodbye.