Difference between revisions of "PHP-and-MySQL/C2/Loops-While-Statement/English-timed"
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| − | |Hello and welcome. I have decided to create separate tutorials for each | + | |Hello and welcome. I have decided to create separate tutorials for each '''loop'''ing '''statement'''. |
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|00:07 | |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. | + | |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. |
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| − | |In this tutorial, we will learn about the '''while''' | + | |In this tutorial, we will learn about the ''''while' loop'''. |
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|00:21 | |00:21 | ||
| − | |A '''while''' loop checks for a '''condition''' at the start of the loop and | + | |A '''while''' loop checks for a '''condition''' at the start of the loop and '''execute'''s the '''code''' depending on whether this '''condition''' is '''True''' or not. |
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| − | |My '''condition''' is here. Now, in the '''if''' statement, for example I used 1==1. | + | |My '''condition''' is here. Now, in the '''if''' statement, for example I used '''1==1'''. |
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Latest revision as of 21:11, 15 December 2018
| Time | Narration |
| 00:00 | Hello and welcome. I have decided to create separate 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 of 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 my 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 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, let's try this. |
| 01:22 | It would probably crash your browser because the loop would be repeated as long as 1=1 and for infinite number of times, 1 will always equal to 1. |
| 01:34 | So, since the loop will always be repeated, your browser will crash. |
| 01:40 | Let's say while a variable '$num' is smaller or equal to 10 and under echo I can say: $num ++. |
| 01:57 | '++' is an arithmetical operator. What it basically does is, it increases 'num' by 1. It is the same as writing 'num =num +1'. |
| 02:16 | So, it takes 'num' and says that it is equal to the value of 'num plus 1'. |
| 02:23 | So, this again is an arithmetical operator. What's going to happen is - |
| 02:29 | we are going to say 'num' less than or equal to (<=) 10; if 'yes' then echo Loop and then say add 1 on to the variable 'num'. |
| 02:41 | But, what we should really do is create '$num = 1' at the moment. So Loop once at 1. This will then equals to 2, then 3, then 4, then all the way up to 10 and then this 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 we will we get. Okay, we got 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 '$num' inside - it will make it much easier to read. |
| 03:37 | Okay. I'll say loop 1 and add 1 and then I'll say loop 2 and I'll add another 1; and that's loop 3 and I'll add another 1 up to 10. |
| 03:49 | Let's open this up. Refresh it. There you go. You got loop 1,2,3 all the way up to 10 as you can see. |
| 03:58 | Let's change this value here to 100. Refresh that. You can see it has gone to hundred. The bigger the number, the longer it will take to loop. |
| 04:08 | Let's take 6000. Let's refresh that. It's going to take a while. There you go - up to 6000. So it's very efficient in this way. |
| 04:20 | You can try combining this with an array to create a program that echoes out the alphabets inside the array. |
| 04:27 | You can use loop to echo out every single value of an array. |
| 04:32 | Just give it a go. I will probably do this in one of my tutorial - not in the basics section though. |
| 04:40 | However, this is the basic structure. What I also recommend you to do is, create a variable here called '$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 summarize. 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. |
