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(piano music)

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-: In this video, let's talk about operators.

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That's right.

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You can perform operations on different values.

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In fact, we have done that before,

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but let's expand the examples and more operators.

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So, basically we can add two numbers,

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we can subtract two numbers,

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we can divide two numbers,

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we can multiply two numbers

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and also we can perform an operation,

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so that you will get a remainder of an operation.

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Okay, so when you divide a number

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and if you only want a remainder, we can do that as well.

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So, let me show you those things with code here.

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So, what I will do now is first of all,

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let's create two variables

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and of course we can name any variable name.

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Let's go with integer num1,

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and the value, it will have, let's say seven.

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And then let's have one more variable here,

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which is, let's say five, num2 is five.

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And then I can perform some operation

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and I can save that operation in a result.

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So let's say if you want to add two numbers, we can do that.

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We can save the output in result,

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and then to perform the operation,

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we can use a plus operator.

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That's right, we can actually use a plus operator

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to add two numbers.

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And then once you have done that,

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we can simply come back here.

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We can say system dot O, dot print, Ellen,

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and here we can print the result

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and just to see if it is working.

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And as we discussed before,

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this is not a good way of running a code.

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You have to first compile the code, then run.

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But we got a shortcut, I can simply use Java space file name

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with J, with dot Java.

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Say Enter, and we got 12.

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So when you say seven plus five, we got 12, cool.

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Now what I will do is, so we can add two numbers.

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What about supply action?

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Let's try that.

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So I will say minus symbol and run.

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You can say we got two.

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So just working.

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So we can add two numbers,

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we can supply two numbers.

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How about multiplication?

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We can do that.

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So we can say star num1 into num2.

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Come back here.

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Run, you can see we got 35.

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So seven into five is 35.

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That work, that is working.

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How about division?

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Let's try that.

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So the moment I said division, we have

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to use a slash.

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Okay, so we don't have a division

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in fact, that's how we do, right?

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We underscore or something with a slash.

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So yeah, we got slash, let's try and you can see we got one.

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That's right.

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One is a question here, right?

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So when you divide seven by five, you get two things.

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One is a question, which is one,

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and then you will also get a remainder.

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Now in this case, when you use slash,

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you will only get a question, not a remainder.

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So how will you get a remainder?

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In that case you have to use a modulus operator.

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So we can use, when you say percentage symbol like this,

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it is a modus operator that

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what it will give you is only a remainder.

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So if I run this code, you can see we got two,

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two's a remainder here right.

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Now We can use any complex numbers as well,

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whatever number you want to perform with,

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and I would suggest you to try a certain example so

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that you'll get the, get used to this operations.

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Now all this operation actually makes sense, right?

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These are very simple stuff to understand.

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Can we use some other operators as well?

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Let's try.

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What I will do now is let me just remove this result

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for time being, or maybe I can just comment this part.

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I also don't need this num2, let me only focus on the

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first variable, which is num1.

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Now, let's say I want to add this num1 by two.

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So basically the value of num1 is seven.

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I want to increment the value by two.

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So what we can do is we can say num1 is equal to.

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So basically we have to use num1,

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which is num1 in this case,

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and we'll add a value to it, which is two.

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And then whatever new value you will generate

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after this will be assigned to num1.

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Okay, that looks cool, right?

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Let's try this.

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I will say num1, between num1,

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and let's run this code.

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You can see we got nine.

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So this is working,

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so seven became nine.

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So just working right.

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Now when you know

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that you are adding the number by itself, okay,

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what you can do is you can just use a shortcut.

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Now what that shortcut says is,

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let me just comment this section here

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and let's write it fresh here.

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So we'll say num1, see you want to increment the value

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of num1 by two, right?

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You want to add itself by two.

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So you can say, I want to add myself, but how much value?

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So I have to say equal to two.

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So what we're saying is we want to increment num1

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by two, even this should work.

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Let's try, oh, we got an error

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because I forgot the semicolon.

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And let me just clear this, run.

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And you can see we got nine.

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So this is working, cool.

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Now it's not just variation, we can do that

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for any other operation.

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Maybe you want to subtract a number by two.

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So we can say subtract equal to two.

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So it will reduce the value by two.

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You can see got we got five, we can multiply

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with some other number.

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Maybe I want to multiple the same number

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with another number and assign it.

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So we've got 567 into 856.

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We can divide as well.

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And so you can use slash

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and all the operators, which you have.

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Awesome, so this is shorthand.

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Now going back to the additional operator,

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and then let's say if you want to add it by two,

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we can simply mention the value two, right?

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We can also add it by one.

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So in this case, if you say added by one, the value

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of num1 is seven, and then you are adding it by one.

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You can see we got eight.

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Now in fact, there's a shortcut for this as well.

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What you can do is instead of using num plus equal to one,

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you can also say num1 plus plus even this is possible,

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let's remove the space in between.

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So even this is possible, you can say num1 plus plus,

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which is incrementing.

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So what we are doing here is something called increment.

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And if you're on this call, you can say we got eight.

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So this operation, let me just make it one.

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So all this operations are similar.

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Okay, so why I'm saying similar, why not same?

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We'll discuss that in some time, but this is similar

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and maybe we have done that before as well.

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When we talked about characters, you know,

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we remember C plus plus, we done that.

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So yeah, we are incrementing here as well.

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Now, not just incrementing, we can do decrement as well.

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So instead of saying numb plus plus,

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we can also say num minus, minus.

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So what we are doing now is decrement.

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So when you say plus, plus, that is increment.

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Let me comment this part.

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And here I will say num minus minus.

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Now why you have

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to commend this, but I want to run this.

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So we can say now minus, minus,

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let's run this code if, see if this works.

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And you can see we got six.

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So that's how you can perform this addition,

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subtraction, multiplication, division,

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and increment, decrement.

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In fact, we have also talked about modulars, which is

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for finding the remainder.

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Okay, now that was about increment decrement, right?

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We have talked about that.

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Now, instead of using plus plus we can actually use

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something called, let me just write it in comment.

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So instead of saying num1 plus plus,

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we can also say plus plus num1.

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You know, just to simplify this example, instead

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of saying num1 everywhere, let's say num, so

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that maybe you will not get, you will get confused by

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that one extra symbol there, which is one,

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just ignore all this operation, just focus on this part,

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which is num and num.

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Also, remove this, also remove this.

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Let's see if this is working.

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Okay, this is working.

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So basically we can also say instead

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of saying num plus plus, we can also say plus, plus num.

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Now what's the difference between this two?

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Even this also work.

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Let me just try that and show you.

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You can say we got eight, we are incrementing the value.

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Even this will give you eight.

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But what's the difference?

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What's the difference between writing this afterwards

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and writing before the variable?

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So basically we have a different names to it.

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So whenever you perform operation

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after the variable, maybe it is for additional

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or supply, it is for increment or decrement.

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So when you do it post, we say it is post increment.

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And when you do pre

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before the variable, it is called pre increment.

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Okay, so when we are doing it afterwards,

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we say post increment.

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When you say before it is doing pre increment,

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now you might be thinking, hey,

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ultimately the value is same, right?

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So even if you pull, even if you do this

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or this, both will increment the value.

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Then why we have two different syntax for it.

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Why not just simply one?

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The answer is it behaves differently when you try

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to assign a value, when you try to fetch the value,

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let me repeat, these two operations will behave differently

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when you try to fetch the value.

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Okay, let me tell you what I'm talking about.

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Let me show you it here.

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Let's come back here

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and let's say I have a different variable, which is int,

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and then I'm storing that in result

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and what I'm storing is num

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or maybe I will say plus, plus num.

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Okay, now think about this and maybe you can pause the video

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or whatever you wanna do.

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Just think about what will be the value of result.

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I will say result here to print,

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and maybe you have done your thinking, let's run this

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and you can see we got eight.

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So what is happening here is the initial value

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of num is seven.

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And then you are saying plus, plus plus num.

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That means you are incrementing it, that

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incremented value will be assigned to result.

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And then you got result, which is eight.

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So initially I've also mentioned

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that this two will be incrementing.

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So we can also say num plus plus, even they should

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be doing the same thing, right?

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Let's try, oh, there's a twist here.

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So plus plus num and num plus plus are not same.

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I mean it works same with their individual statement,

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but when you try to fetch the value from them when they're

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performing the operation, they behave differently.

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So let's understand why it is called pre increment

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and what is called post increment.

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So whenever we use assignment operator with this operation,

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what it will do is it will check, hey,

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we have an operation which is num plus plus,

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but that's a post increment.

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So first it will fetch the value of num, let me repeat.

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It will first fetch the value

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and then increment.

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In fact, it looks like one statement,

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but we have two statements here, right?

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In fact, we have this statement here,

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num one equal to num plus one.

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So what it'll do is it'll first fetch the value of num,

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which is seven in this case,

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and then it will increment the value of num

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and will make it eight, okay?

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But then what is assigned to result is seven itself,

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and then you are printing that seven here, okay?

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But what will happen when you

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say, let me just write it here.

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So we'll say end result is equal to plus, plus num.

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In this case, what will happen is it will first increment

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and then fetch the value, okay?

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So it will first increment itself

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and then it will fetch the value.

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And that is what is going in result.

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I hope this makes sense, right?

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So this is how your code works when you say plus, plus num

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and num plus plus, in fact, we'll do some more operations

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with this once we get started

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and it will make much more sense later.

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So in the operators, we have talked about other

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thematic operator until this point.

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So whatever option you have done, it is

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for the Arithmetic purpose, right?

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Addition, subtraction, multiplication, and division.

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But what if you want to compare to values?

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What if you want to have compound conditions?

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Okay, what are those things, we'll talk about

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that in the upcoming videos.