Logic: If/Else If

Quick reference

• 00:04 Okay so we've looked at if else statements there's also an if else if statement.
• 00:08 So it gives you even more control over your logic.
• 00:12 It allows you to make separate comparisons slightly differently than the and
• 00:17 and the or.
• 00:18 So in and and the or we were able to compare more than one thing.
• 00:21 In an else if statement, we can make an entire other argument, question, right?
• 00:27 And so let's just run this and see.
• 00:28 Let's redo our else statement here like we did earlier.
• 00:32 And let me just copy this guy.
• 00:36 And here we want is not greater.
• 00:38 So, here we can say if a is greater than b, then we want to do all this stuff.
• 00:43 So, if we save this and run it, we see 20 is greater than 19.
• 00:49 But what if we wanted to ask another question so to speak?
• 00:52 Well, we could do that.
• 00:54 Right here, we can go else if and then we can do an entire other statement.
• 00:59 So we could say else if a = b right,
• 01:02 then let's just copy this guy paste it in.
• 01:07 And let's say is = b.
• 01:12 So if we save this and run it,
• 01:13 nothing's really going to change here because 20 is greater than 19.
• 01:18 So what happens is anytime you're using any sort of if else or if else if blocks,
• 01:23 your program is going to start at the top and it's going to work its way down.
• 01:28 Anytime it evaluates to true,
• 01:31 it will execute the next block of code and then stop, right?
• 01:36 So if we get to this and we say, this is true, it will spit this out and then stop.
• 01:41 It will ignore all of the rest of these things.
• 01:45 But if it comes down here,
• 01:46 evaluates this as false, it'll drop down to the next thing, this one.
• 01:51 If this evaluates to false, it'll drop down to this one.
• 01:54 And then finally spit this out.
• 01:56 If if there's no true things by the time we get to the end, the else,
• 02:00 then the else gets executed, right?
• 02:03 But if at any time we hit true, it stops.
• 02:06 So let's change this around.
• 02:07 Let's go 20, so here we start out is 20 greater than 20?
• 02:14 No, it's not this is false.
• 02:15 So it's going to skip this and it's going to go to this.
• 02:18 And it's going to we have a whole new question to ask here, does a equal b?
• 02:23 Well, 20 does equal 20, so it will execute this line and then stop.
• 02:29 If this was false, then it would finally spit out this.
• 02:31 But this one is true, so we should see this on the screen.
• 02:36 So let's go ahead and save this and run it.
• 02:38 All that build up, 20 is equal to 20, all right, cool.
• 02:43 If we change this again back to 19 or 10, or anything else,
• 02:47 we could walk through this again is 19 greater than 20?
• 02:51 No, it's not, so hey, skip this.
• 02:54 And we come to this hey, is 19 equal to 20?
• 02:57 No it's not, so skip this.
• 03:00 Then execute finally whatever this is.
• 03:03 So if we save this and run it we get, as we expect, 19 is not greater than 20.
• 03:10 So that's how you use an else if statement.
• 03:12 Now, you can have as many of these as you want.
• 03:14 You can have 50 else if statements,
• 03:17 you can just keep under each one keep going, and just keep doing things.
• 03:21 And you can have as many of these as you want.
• 03:24 It will just bang, bang, bang, bang, start at the top keep going down until it finds
• 03:28 something that's true and then it will execute right after the true thing,
• 03:32 whatever is in these brackets, and then stop.
• 03:35 So that's if, that's if else, if else if, that's comparison operators, that's logic.
• 03:40 That's really all you need to know in order to do some pretty powerful coding.
• 03:44 And as you can see, it's pretty simple.
• 03:46 And that's all there is to it.
• 03:47 So that's it for this video.
• 03:49 In the next video we'll look at switch.

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