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Friends, in our previous video we have seen about arithmetic

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and assignment operators of Python.

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Now, we are going to discuss about the next operator,

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that is comparison or comparison operators of Python. Guys,

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these operators are very, very important in your real-time,

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comparison operators.

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And one more point, we already discussed that while giving

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introduction to operators, that is, comparison operators

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we take input as value, right, and then it will give output

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as a Boolean value, 'True' or 'False'.

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Right. See actually comparison is nothing but finding relation

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between two operands or two values.

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I mean, let's say you have 3 and 4, numbers. Now I am going

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to check '3 > 4', no, 'False', no. We know that 3 is

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not greater than 4 that's why this is a comparison operator

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here. And if you compare these two with the help of this

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'>' symbol, right, you are going to get result as

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'False'. So we are providing input as a value, number, number

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system value, right, as of now, and output you're going to get

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either 'True' or 'False', right?

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Let me open my Python terminal so I can explain very easily from here.

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As of now we are not going to write any Python program or

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script. Let me take '3 > 4', no. We know that. 'False'.

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See guys, while taking your comparison operators you can

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take a space of between your operands.

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Now, let me take '3 < 4'.

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Yes, we know it is 'True'

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exactly. Even if you do with Python, you're getting 'True',

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right? So comparison operators are used to find the relation

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between two values or two operands.

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So guys, I can also store my value into some variable, and

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now I am checking '3 < a', so what is 'a'? Value 4.

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So Python is going to compare like '3 < 4'. See internally

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'a' value is nothing but 4, so '3 < 4'.

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Yes, it's 'True'. Right.

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Let me check it, yes.

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So likewise you have different types of operators here, > ,

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<, ==, '==' means equality,

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!=, >=, <=,

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right. See directly you can check suppose 4 <= 4

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See actually the meaning for this is, it may be less than

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or it may be equal.

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If anyone of the that is 'True', then you will get output as 'True'.

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I mean 4 maybe equal to 4 or maybe less than that.

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So as of now in this relation 4 equals to 4, but you are

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checking either less than or equal.

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So equal is correct, that's why we're getting 'True',

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or instead of that

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I'm taking 3 <= 4. Yes,

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anyway 3 is less than 4, 'True'. Maybe anyone of that, either

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less than or equal.

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Right. So guys one one more thing using this comparison or relationship

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operators with the number systems is very easy, because we

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are very much familiar with the number systems from our mathematics.

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Directly we can see by seeing your numbers, two numbers, two

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values, you can tell the relationship between those two

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numbers either equal, or not equal, greater than, less than,

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less than or equal to, greater than or equal to, right but

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when you go with the strings, actually strings is also important

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while discussing about your comparison operators.

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I mean how to compare strings.

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Let's say I have a string called "a". I want to check

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this, either 'a'=='a'.

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Yes, it's 'True'.

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'a'=='b', no. These two things directly we can tell

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that, or 'a' != 'b'.

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Yes, it's 'True'.

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They are not equal.

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We are checking they are not equal. Yes, 'True'.

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So equal and not equal we can easily understand because by

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seeing strings itself we can match and we can tell that whether

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they are equal or not equal.

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But what about this?

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I am telling 'a' < 'b'.

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Yes, it's true actually. But if I run this, yes, you are going

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to get output as 'True'.

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How your Python is going to compare your strings?

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What is the mechanism while comparing your strings?

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Nothing is there, guys. Whenever you are going to compare your strings

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your Python will convert each and every character into an

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ASCII code, based on ASCII code it is going to compare. Let me

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find what is the ASCII code for your 'a'. See to find for any

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character the ASCII code, the default function is 'ord'.

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'ord()', your character.

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Not only 'a', you can take any special character

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also, you are going to get some ASCII code. No need to remember

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that, but at least just try to remember the function. See

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if I know ASCII code then how can I find

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character. Let me write it, chr(45). See that. You can find

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your character ASCII code using 'ord' function.

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You can find the particular character from your ASCII code

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using 'chr' function.

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That's fine. Now let me compare 'aa', is it less than 'b'.

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Yes, obviously it is true.

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The reason is, whenever if you have multiple characters,

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right, the first character from your left side string will

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be compared with the first character from your right side

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string. So 'a' < 'b', we know that. That's why it is 'True'.

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Let me take something like 'abc', and I'm going to take 'z'.

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Otherwise I will take 'aa',

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or 'aaa'. Let's say 'c'. Now,

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the result is 'False'.

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The reason is, first thing, first character from your left

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side and first character from your right side of your operator

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is 'aa', both are equal. That's right.

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We'll skip that, and we'll try to compare second characters.

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So 'b' is greater than 'a', right. But you are checking less

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than, that's why this is 'False'.

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Right. So it will compare character by character in a given

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string. Right?

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Likewise, suppose if I do '>' symbol, then it's 'True'.

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Right. So simply guys your Python will compare your strings based

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on an ASCII code.

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So how to get your ASCII code is nothing but order of your

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particular character. How to get your character for your particular

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ASCII code, 'chr' function, right?

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So guys these comparison operators are very, very helpful while

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discussing conditional statements like if and if-else, else-

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if, nested ifs, right. There, we will use effectively this comparison

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operators. As of now what you have to remember is comparison

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or relationship operators will take input as either number

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or a string and it will provide output as always, always output

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will be either 'True' or 'False', because you are comparing, you

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are checking the relation between two values.

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That relation is like, are they equal, are they not equal, if anyone

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of that is greater than, or less than, less than or equal to,

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greater than or equal to.

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So you are checking relationality between two values,

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so that is nothing but the output is always either 'True' or

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'False', or simply Boolean output.

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Right. Okay.

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Okay guys, thank you for watching this video.

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