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[no audio]

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Friends, here we are going to see

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the simple usage of your functions that

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is converting given code in terms of functions

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without changing the output.

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Actually, I have a simple Python Script.

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This is the Python Script, and this is the output for that.

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Now, I want to implement this code in terms of functions.

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Friends, we know that. Generally we use the functions whenever

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there is a reusability, right? Not only for that, assume that

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you have some thousands of lines in your code.

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Instead of writing line-by-line thousand lines in your script,

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it's better to divide your entire program into some parts

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based on the logic.

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I mean, if you observe our code we have six lines of code, right?

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Assume that first two lines are for simply like welcome

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message, right, and second two lines represent suppose,

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this is whatever the concepts you know, known concepts, right?

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Just assume that, known concepts. And last two lines are your learning concepts.

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[no audio]

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Now if you observe my entire script, I can divide into three parts.

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One part is welcome message,

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second part is known concepts, third part is learning concepts.

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So if you divide your code in terms of three parts, then

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readability is more, right?

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Now, functions are not only for reusability purpose,

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it is also for readability purpose.

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[no audio]

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Right. Just assume that you have thousands of lines of code

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and you implemented today. And after one year you're coming

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back and you're going through that logic. Directly you can't understand

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what is the logic you implemented. Instead of that

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if you divide your code in terms of some separate parts,

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then by seeing each and every part you can easily understand

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this part is so-and-so purpose, this part is so-and-so purpose.

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Right. So that's why if you try to implement your code in

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terms of functions, then there is more readability.

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Now for that

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what I am doing is, anyway it is a very simple example,

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but just to get you idea on functions

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I am trying to convert this code in terms of functions.

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So before going to convert, guys already we know, if you want

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to write a function, right, you need to define functions, right?

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So you know how to define a function as well.

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You have to use 'def' keyword, then some name, right, some

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name, anything, right, some 'xyz', then '():',

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then you have to write some number of lines based on your

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requirement, and finally you have to write 'return None', right?

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We'll discuss about 'return', but this is the standard syntax

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to write your function as of now.

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Now what I am doing is, I am trying to divide my logic, six

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lines of logic into three parts.

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So in first part I am taking these two lines, and I am implementing

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in this way 'def welcome_msg'. That's it.

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Then inside of this function, I am going to write these two lines.

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Right. Finally, I have to write 'return None'.

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Then I am going to define one more function that is, suppose

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'def known_concepts'.

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That's it.

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Then whatever the lines you have in you your known concept,

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suppose these two lines for my known concepts logic,

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just assumption, nothing is there.

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How you can convert your code into functions.

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So for that just I am giving idea. 'return None'. And we have

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two more lines. For these two more lines

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what I am doing is, I am going to divide again that as suppose

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new concept or learning concepts.

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Let me take suppose 'new_concepts()'.

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That's it.

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Right. And finally just write 'return None'.

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So now whatever the logic you have, that logic now I am implementing

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in terms of functions and I'm running this, no output.

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We know that if we define simply function you won't get

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any output. To get the output, whatever the output you need

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that particular function you need to call, right. See, suppose

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I want to get 'known_concepts' logic output, then I will call

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in this way, function name, parentheses. That's it.

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Let me run it and see the output. You are getting.

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But actually I need to get first these two lines,

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then these two, then these two, and the same order you just

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call your functions. Very first you just call your function,

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that function as 'welcome_msg'.

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Then last one 'new_concepts'. That's it.

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Let me run it and see the output.

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Yes, you are getting. Now what we did, whatever the logic you

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have, but actually this logic consists of three parts

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Just I'm assuming. First two are something like 'welcome_msg',

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second two are something like 'known concepts' logic,

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the last two are for 'new_concepts' logic. Based on that just I have

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given some names and I'm calling them.

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Right. So guys if we change this order, this functions called, the

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way how you're calling know, this order, you will get based

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on that order only you will get the output.

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Right. And one more thing guys, see

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if I remove these three functions names to call your defined function,

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you're not getting output by running that code. The reason

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is, whenever if you run your code Python will run from top

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to down. While running from top to down whenever there is

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a 'def' key word, at that time your Python

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won't execute that logic or block of code which

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is there under your function.

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Simply your Python will remember the name of your function.

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Same way if you observe all places you have simply 'def',

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there is no straight forward line or main line

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that's why you're not getting any output.

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But if I write in this way,

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[no audio]

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now only this part is defining

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your function. Now directly you're calling, so your line of, I mean

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your execution part will start from thirteenth line.

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So from this your Python will go here, and will execute here,

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and will come back.

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So after that line in case if you have one more function

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or same function maybe, in case if you want to print welcome

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message two times, yes, no problem

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you can print it. Now see the result. Two times you are getting.

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But I want only one time.

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Yeah, no problem.

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[no audio]

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That's it. Now see the result.

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Okay, so guys this is just I am trying to give some overall

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idea. In case already if you have some logic in your hand how

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to convert that into in terms of functions.

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Right. So while going forward we will discuss in detail about your

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different types of functions.

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Anyway, we are going to discuss about user-defined functions.

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Built-in functions, already

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we discussed something like 'list', 'integer', 'length', right, 'id', 'char',

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something like that, default functions

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which are defined with your Python.

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Now, we are trying to define our own defined function. User-defined

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function we are defining, and we are calling them, right?

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Okay guys, we will see in detail while going forward.

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Okay, thank you for watching this video.

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