All language subtitles for 13. Logical Operators 1 - Can we use Relational Operators on Structs by default

What is going on, ladies and gentlemen, and welcome to this very, very important video in our programming

course as well as in your programming career.

So in this video, we are going to talk about a couple of things, but mostly we are going to talk about

how we can use relational operators such as smaller, bigger or smaller or equal, bigger or or equal,

not equal or totally equal using structs.

OK, so we know how to use relational operators with just some standard variable standard data types

such as integers, floats, doubles and so on.

But now what we are going to do is to take a look at how and if we can take advantage of these relational

operators and use them between different variables of certain struct.

OK.

And we will see that it's not so trivial, and it's not kind of very, very easy and intuitive, but

we will need to think of a way to find out how we can implement what we are looking for.

OK, so I think that the best way to start these explanation is just by giving you these little nice

examples that you can see on the screen.

So we are going to take a look at two different structs, and hopefully by the end of this video, everything

will be clearer to you.

OK, so that's something we will refer right away.

So let us, first of all, start with this typedef struct point.

So we have the structure of point.

Nothing can new so far.

And we are going to take a look at how we can create two variables of these struct.

OK?

The first variable will be B one.

And the second variable will be to one of them is going to be with the values of three and five in the

second one with the values of two and six for X and Y.

Respectively.

OK.

So we create two objects initialize them, and then what I want to ask you is a simple question if we

can or not compare between them.

I mean, I want to find out and write these kind of logical tests.

I want to see if P1 is greater than P2.

And that's something that is very important to understand.

We compare now not just between two integers.

OK, so we know how to find which which of doing the jurors is greater, which is the smaller and so

on.

We also know how to do it for floats and doubles and so on.

Now we tried to compare between two variables of a user defined type.

For example, point that we've just created.

So the question is, how should you compare between and B2, let's say you want to find out if B1 is

greater than B2, then to run some code lalala and then to print that point one is greater than point

two.

OK.

Basically, associate some code with with the answer to these condition.

But the question is how can you even think about comparing B1 B2 to variables of a point type?

I mean, what fields will be used to decide the result of these condition?

What fields would you like to test?

Would we like to know only if B1 is greater than B2 just by using its ICS field, just by comparing

the ICS data member?

Or maybe would like to know if it's decided by one by five by five by white.

So, I mean, if we take a look at P1 and P2 and we ask which one of them is greater than the other

in correspondence, do the X value.

So we can say definitely that P1 is greater, right?

Because P1 died three and P2 X is two.

So we can say that in correspondence do the X value P1 will be considered greater.

But if we will take a look by the Y value of these two variables, we can see that P2 has a y value

that is greater than the Y value in P1.

OK, so how can we say which one of them is greater than the other?

OK.

For that, we will need to specify, but exact by exact what fields we want to compare between these

two variables of struct point.

So in this case, that simply won't work because.

We do not specify exactly by what fields we are going to decide the result.

OK, so it may be by one of them, it may be by both of them, it may be by none of them.

I don't know.

It depends.

So up until now, just understand what you cannot do and you should not try to do.

OK, so that's the problem.

Number one, you cannot compare between them.

You cannot ask if one is greater than P2.

The second is also to demonstrate basically, what are you trying to compare?

Are you trying to compare both of these variables field by field?

If that's the case, maybe we can write something down, but not always.

That's the case, will not always.

We compare between two different variables of this same structure, and we want to know and to say that

they are totally equal only if all of their fields are totally equal with one another.

That's not always the case.

OK, I'm going to show you hopefully during these course, a couple of scenarios where this wouldn't

matter.

OK.

So error number two, we don't know what fields are we interested in.

Maybe we are interested in all of them.

Only if all of the fields are equal, then the result will be true.

Or maybe we are just interested in knowing if P1.6 equals to P2 italics, then we can say that for us,

that should be sufficient.

And we can say that both of these variables, B1 and P2 are equal just by saying that if the X members

are equal, then we can decide and we can conclude that both of the variables of struct point are equal.

So we didn't specify it explicitly.

So that's hard to decide.

OK.

So far, so good.

I'm just preparing you for a material that is even more important and not not more important, but also

very important.

So that's about the first example.

Now let's take a look at the second example to make sure that we understand the small details.

OK, so we have these struct struct employee, and this structure is basically it consists of three

fields.

The first field is an array of characters.

The second field is a float age some variable and the third field is end ID.

OK.

Three fields.

The first one is an array.

The second one is float.

The third one is entry I.D. So we want to ask a simple question.

OK, let's take a look at this code that I've added here we have created to object to two variables

of an employee struct.

So we created empty one.

It is a variable of a struct employee initialized with the next values.

OK, and the same we do four empty two.

So the first one is Jake.

He's 24 and a half years old and his ID is one two three.

And we also have the second employee MP to which is John, and his age is 30, and he's IDs three four

two.

OK, so far, so good.

Now what we wanted to know is if we are to compare between these two variables of this structure struct

employee.

Then basically, also this will not work.

OK, I.

Intentionally intentionally giving this emphasis on this topic, because a lot of students, they find

it hard to understand the next topics that you learn, like how to use basically in C- language, how

to use the functions that are related to it in C++ language, how we can and why we should use openly

operator overloading.

OK, so that's just the basics.

Make sure you understand it completely, not just memorizing it, but understanding every step that

we discuss here.

Why is this happening?

Why is it not working and so on?

So we cannot compare if MP one is greater than MP two?

Because by what fields do we exactly compare between them?

Do we compare if MMP one is greater than MP two just by comparing the field of the age?

Or maybe maybe we ask if MP one is is older than MP two.

That's one option, but maybe we want to ask you for MP.

One is greater than you do, then it simply means that we want to compare their IDs who appears before

who in the I don't know, in some book.

OK, and also the same goes for the name which name appears first or maybe will want to take into consideration

all of these fields?

OK, so that's why you cannot work with it.

OK.

And you basically don't know, are they equal by ID, by name or all of the fields?

OK, so that's the problem that we have in the solution to this problem.

I'm going to give you in the next video.

OK, so stay tuned.

Let's go.