Difference between revisions of "PHP-and-MySQL/C2/Loops-Do-While-Statement/English-timed"

!Time

!Narration

|Welcome again!  In this tutorial, we will learn the DO-WHILE loop.

|Its also called the DO-WHILE  statement.  You can choose to call it a loop or a statement.

|The base is similar to the WHILE loop, although the condition is checked at the END of the loop as opposed to the START.

|We have DO, our block with the curly brackets, and WHILE  at the end.  Then a condition in here.  So this is the condition.

|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.

|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.

|I'll type num = 1 to start with.

|Then I'll type my name is Alex.

|The condition of the loop I want is - while the name = Alex.

|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.

|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.

|Now what we type is DO.

|Firstly, echo out the value of the number.

|You can concatenate that with a brief HTML code to break the line.

|Here I type num++ which is the same as num +1

|Then my IF statement - If num is greater than or equal to 10 then no echo.

|I want to change the name to Billy.

|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

|Therefore I just need one line code because it looks neat.

|This is my number variable, this can increment and can be echoed out to the user.

|I've got my name set to Alex.

|We start our DO.

|The name is still Alex.

|There's no condition so this will run regardless of anything

|03;07

|So we echo out the number which is 1

|We increment it by 1 which will equal 2

|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

|It isn't. So skip this. It'll go on to say name = Alex.  And then go back to the top.

|This will still be 2.That means the loop's stuck at that block of code.

|It'll echo out 2

|It'll add one and say 3

|And then it'll say, is 3 bigger than or equal to 10.

|Now, it's not.

|So, the name is not changed to Billy instead it'll carry on with the rest of our code.

|The name's still Alex

|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

|Now num will become 10

|The IF condition will be True.

|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.

|So lets execute this code. Do our loop.  Click on that.

|OK, we've got 1 2 3 all the way up to 9.

|Obviously, our condition has been met. Our name has changed to Billy.  Our name doesn't equal Alex anymore.

|So, our loop here has stopped.   

|Now change the IF to 11 or you can change num to 0

|Now this won't work and you'll see why  

|We've got 0 to 9

|The reason being is your starting number

|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.

|If you change this to 11, you'll compare it to 11, then change it to Billy and then it'll end the loop.

|If we refresh this,  we can see there's 1 to 10 now.

|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.

|So, practice this, try and enter some values.  Also, try to recreate the program I've just created.

|There will be more tutorials on loops shortly   So keep watching.

|This is Anoushka dubbing for the Spoken Tutorial Project.