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Hello and welcome.

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Today, we will kick off with a new topic, which will be if conditions, statements, if conditions

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is a meaningful part in programming in general and in Python specifically, if conditions have strong

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connections also to the next topic, which will be Loop's.

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And let's go straight ahead for the theoretical part definition.

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So if is if condition is an ability for decision making.

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In other words, sometimes in our call we would like to take a certain variable or a certain collection

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and decide what happens if the value that we are dealing with will be will be equals for something or

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it will be bigger than something.

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And what will happen if our if condition, meaning our question will be true, then we would submit

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a certain part of the code.

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And if the result will be false, we would like a different code to run.

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So this is decision making in summary.

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So if condition is an ability for decision making and for that if conditional statement was created,

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also known as if else statement, meaning if you encounter this term, so this term and if conditions

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is the same.

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So in computer science and if statement gives it an ability, the ability to execute a bulk of code

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for a choice for your choice, only if a certain condition is satisfied.

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This happens as the result of an if statement is a true or false boolean value, meaning the output

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of an condition could be only two options, true or false.

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And then we can decide what happens if the value of the if condition is true and what will happen if

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it's false.

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So let's start off with a simple syntax example here.

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We can see and if conditional example or this part right here.

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So first of all, we're defining here a variable X and it's equal to three.

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And then we're asking the if condition right here.

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It's right in here if X is larger than four.

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So if you'd like to cast it, as you might say, to human language, this is a question.

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This is a question we're asking is if bigger than for it's a question and if the answer is true.

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So you can see an indent right here.

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This is the intent of the if so if the output here is true, boolean boolean value true.

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So please print out this bulk of code.

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And if it's false, then the code flow will go straight ahead to the else part and it will print the

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value.

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No, it's very simple.

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All right.

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So it's a question if the answer is yes.

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So print this one if the answer is true, to be more accurate.

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So print this bulk of code and if it's false, then go get out of the F and go to what you have in the

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else.

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This is like the default exit point, meaning if this value ratio is false, meaning if the value right

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here is false, then go to the default exit point, which will be the errors and run what you have under

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the else.

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So this is a quick brief.

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All right.

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Right here.

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Let me just fix it.

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This and this, yeah, so let's I'm going to repeat several times on what we just discussed right there,

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one of the ones of you that got the hang of it, just go and play.

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Fast forward the following minute.

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But for those of you who have trouble to get the concept, I'm going to repeat it several times so we'd

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go deeper into your DNA.

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All right.

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So follow steps.

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So we have here also a sketch of the flow, the call flow.

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So what happens here?

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Basically, I'm explaining what happened here.

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All right.

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So first of all, we start the program, we start the class, we run the class that this bulk of code

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is in it.

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So we started.

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Then we encounter and if condition.

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Right.

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This is the yellow part right here.

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And then there is a question in the if condition if the answer is to run the code back inside the if

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meaning.

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Meaning print.

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Yes.

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And if the answer is false, then run the code back inside or else.

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All right.

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So you have the same explanation right here.

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So what actually like what?

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Like physically will be the output of this one.

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So we declared here X equals three, then we ask X bigger than for obviously the output of this one

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is false.

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So the output of this whole F condition would be print will get the output.

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No.

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All right.

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All right, so in this case, Perrino will be executed as the condition we have, it's bigger than four

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is false.

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So the court under house will run because house is used as a default exit point for the state for if

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the statement is not true.

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Pretty easy, right?

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We have just two options here.

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This or this.

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That's it.

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That's the simple.

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If so, if you get the hang of this one, you now know what or if statements are right.

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And from here, let's go and talk about we have the ALS here, but we also have a term which is ayliffe.

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All right.

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We have ALS and we have Ayliffe.

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So what is the difference between them?

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What's the purpose of else?

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We know already, but what's the purpose of our if we don't know yet?

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So let's hear off again with the theory and see an example straight ahead.

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So as we saw in the syntax example above, that if statement returns a false value, we are only the

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code that is indented inside the else.

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Right, which was print.

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No, but on that's in there, we hope.

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And we have only one condition.

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We asked a single question and we have only two options.

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We can run either prints or print.

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No, we don't have any other options right here.

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All right.

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So we have only one condition.

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It's either true and then we print, then we execute this one or it's a false and then we execute this

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one, right.

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But what if we have lots of conditions to take into consideration and not only one, then we should

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use our if as well.

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And then we ship its duplicates are.

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All right, so Aliev is for all mede conditions while alse is for the last condition that he is used

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as in default exit point for the condition part.

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And let's see an example for this.

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All right.

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Right here.

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We also are going to have X equals three.

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Then we ask a question.

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Does X is bigger?

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Is is bigger than four.

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All right.

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So X is not bigger than four.

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So we have a false here.

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So this would not be executed because false is not executed, is never executed.

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Then we will like to ask another question, Ali, if X bigger than five.

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All right.

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So it's like a continuation of this if.

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All right.

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So if by the way, I wrote here in the sketch bolded in yellow elif stands for or else if I so have

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if x bigger than for false.

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So this one would not be executed then we ask.

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Alice, if it's bigger than five, we just go with the flow from top to bottom, right?

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So after that we ask else if it's bigger than five, also false, then we ask again, else if it's bigger

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than 15.

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Also, it falls here.

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Also a false.

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Right, and then all of these values, all these Output's values were false, boolean false, and then

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we got to the last one, which is alse, and then we just go straight ahead.

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You print five and the only code that would be executed right here among these these conditions right

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here, the only one that would be executed is print five right here.

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And why?

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The reason is the reason is for the last condition that is used as a default exit point, meaning if

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all of these are false, then our code would run what we have here in else.

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This is the default exit point.

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If all of these are output's are false, then else will be executed.

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All right.

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And right here, let's see the sketch.

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So this is the flow that we have just went over and what we basically see here is the start while we

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execute the class, that the cold is in it.

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And then we have the first if condition.

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If the F if condition is true, then run the cold ball inside.

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If this is this part is the same as the previous part, then if it's false, basically, if like we

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have a true so the cold exits the if condition it exits it and continues to the next block of cold,

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the if condition is completed.

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If we have a true value we just continue on.

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All right.

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But if it's a false then we start a different flow here.

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As you can see on the left, we first check is the first el.

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If true, if it's true, round the ball, cold inside the first hour, if then if it's a false all right

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then go to the second el if.

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A condition, and then if that one is true, then Rhonda called in the second ayliffe, if this one

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is false, then go straight ahead to the third one.

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And if the third one is false, then go inside the default exit point.

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Let me just quickly add here the missing parts, because we also need to mention here that what happens,

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whether we have a false value for these you else ifs all right like that.

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And also mention here that.

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What happens if we have a true value for the house?

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If so, let me just put it right here.

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Yeah.

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So I think it's a bit self explanatory because we basically have the same structure and a basic if and

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also in an L if the difference is that in our if we just have several examples of several conditions

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asked and whether in the flow we get a true for one of them.

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So the the code just stops dealing with the if statement just goes on further in the code.

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All right.

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So the flow goes again like this.

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We start the code which first check the main if condition.

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If the main condition is true, we just run the code under it and we exit the condition completely.

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All of these left part here does not run at all.

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Only of the main if condition is false, then we check each and every ELIF.

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And also if all of them are false, then as a default exit point, we run the aspart.

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All right.

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I think this summarize pretty nicely the basic part of conditions.

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And it's a very, very useful and very crucial for you to understand this topic, because I can say

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that a lot of the code that we are going to write further on is based on if conditions and also on loops

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that which we our following topic.

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So try to read this material again.

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By the way, these this document is attached to the current video and Udemy in UDD toolbar.

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And try just to watch that, just to read it again.

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I think it would be very useful and in the next video will try to see more examples in the code in each

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arm and see how can we understand this.

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These flows better.

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We will see both examples for simple if and for if examples in the code in the next video.

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All right.

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That's about it.

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And next, after or after the examples, we will have a quick practice and then we'll go straight ahead

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for the advanced part off if condition statements.

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All right.

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That's about it for this lecture.

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I'll see you in the next one.

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Thank you and bye bye.