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[no audio]

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Friends, here we are going to

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discuss about functions with the default arguments.

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Now to get clarity on your functions with the default arguments,

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let me start with the functions with some arguments.

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Already we know how to pass an argument to your function.

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Right. Let me open my editor.

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Let me create a simple Python Script.

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So I am going to save it as 'fun_with_default_arguments'.

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Now I'm not going to read any value from command line,

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just simply I am writing directly some values.

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Let's say I have simply a function called 'display',

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and assume that this is taking any variable value or argument,

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right, positional argument.

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Let me print("The value of

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a is: ",', just I am printing that

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value. That's fine.

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Then simply I am returning 'None'.

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[no audio]

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Right. Now guys, we have a simple function called 'display',

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and if I run that you're not getting any output because you're

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not calling that. Now let me call that, right?

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I am calling that with value called 4. Now see the result.

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You can also call this function for any other value as well.

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Right. But while calling be clear. While calling in case if

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I do not pass any argument what it is giving?

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"display() missing 1 required positional argument: 'a'."

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Actually, if you observe here this is your defined function.

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Whenever if you want to call this function, this function

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needs one argument, but you are not passing from here.

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Right. You're not passing that. So whenever if you are not

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passing that, you will get an error like this. Now, in case

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if you are not passing then I want to work with some default value.

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If I pass, my function has to take that passed value.

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In case if I'm not passing then my function has to work with

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some default value.

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Let's say I am taking 'a = 1'.

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[no audio]

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Now if I write 'a= 1', see that. Let me save it and

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run it. You are not getting any error. And the default value

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of 'a' is 1. Right. In case if you pass any value, your 'a' is

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taking that value instead of this 'a = 1', right? See in fifth line

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I'm calling your function with the value called 4, right?

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Then 'a' value you are getting 4 here. Observe that. Then second

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I'm calling same function with value 5.

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Yes, you are getting. But third I'm not calling,

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I'm calling without any arguments, then it is getting default

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value called 1. That default value I have given here.

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So this is the way how you can define default value for your

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functions, or default argument, right?

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Now, let me take one more function.

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I will keep this function as it is for your practice.

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Let me define one more function,

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or 'def add_numbers'. Just assumption.

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So if you know the concept, while going forward you can apply

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whenever if you get a situation like this. So actually I

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am going to define a function. This function needs two variables,

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two arguments, let's say 'a,b'.

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[no audio]

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Right. And I want to find simply 'result',

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[no audio]

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it's nothing but 'a + b', and let me simply print directly "The result

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is: ",

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your 'result'. That's fine.

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Then finally, let me 'return None'. As of now

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I'm not expecting anything from my function.

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Now let me call this function with two values.

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Yes, it's working. But suppose I am calling that without any

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arguments, but you are getting an error.

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[no audio]

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Suppose in my hand I have only one value,

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let's say 5. I don't have second value.

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Then you're getting an error.

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So what I am doing is, suppose for second value

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I am giving a default value called 1. Now see the result.

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[no audio]

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But based on situation you need to select a default value.

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Whenever, if you are adding two numbers, right,

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and if you don't know second number, what is the value you

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need to add for first number? Generally 0. That's why I can

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take here now 0.

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So 5 + 0 = 5 only you are getting. I'm calling this function

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with one value only. But what about second value?

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So if it is addition, the second value should be 0. If it is

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multiplication, the second value should be 1.

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So I mean based on your requirement

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you need to select default values, right.

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Maybe some true, false, some path, whatever it may be.

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Right. So if you want to take both the default values, yes you

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can take it. Now see that,

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I am calling my function without any arguments.

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If you are not having any arguments, what is the result?

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Always 0. If you don't have anything it is 0, suppose.

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[no audio]

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Right. But suppose if I give only one argument, so 1 is

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default. But what about first value? You need to pass it.

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[no audio]

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And you need to follow some simple rule here. Suppose if I take

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'a = 0' and then 'b' normally, see that, you are getting

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some error called 'SyntaxError'.

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That is, "non-default argument follows default argument".

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That means always, first you need to, in case if you have some

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default arguments you need to mention always your default

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arguments only at the end while defining your function inside

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of your parentheses.

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I should not write like 'a = 0' and then 'b', but I can

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write 'a,b = 0', means default value

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whatever you have, you have to write at the end in your definition.

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That is the meaning of this error, right. Now see that.

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It's working fine.

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Okay. So guys this is the way how you can define a default value.

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Suppose I assume that I am going to work with some database, or I

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am going to work with some operation on my Linux server.

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Let's say I need a username for that.

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[no audio]

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'working_on_some()', operation, on something, right.

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I need a 'user' for that. Suppose

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If you don't pass any 'user', at least I want to take 'root' as my 'user'.

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[no audio]

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"working with", whatever the '' you have.

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That's it.

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Guys these are just assumptions. Anyway you will get full

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clarity while writing real-time scripts.

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So first we need to learn syntaxes.

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That's what we are doing here.

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So 'working_on_some()'. Now see that. What happened? "'root' is not

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defined". Sorry. This is a string,

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right. That is not a variable, that is a string. You need to

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mention inside of quotations. "working with root". Suppose

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if I know what is the user I want to work, suppose

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I want to work with some 'weblogic_admin'.

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Let's say '("weblogic_admin")'. Now it's working perfectly.

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If you don't pass any 'user' it will take 'root' as the default

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user, but if you pass it will take that passed 'user'.

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So that is the usage of default arguments inside of your

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functions. It's very, very important guys, okay.

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Just try to remember the syntaxes, how we are working with

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the default arguments.

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That's it. Okay. Okay guys,

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thank you for watching this video.

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[no audio]