In our last video, we learned how to add, subtract, multiply, and

divide in objective C.

As you can imagine,

those arithmetic operators play a role in nearly any piece of software.

Just as essential, however, are the comparison operators.

Which as the name suggests, allow you to compare two values, and get a result.

However, unlike the numerical results you would get by doing arithmetic,

a comparison either returns a true or false.

Yes or no.

You're probably already family with some comparisons like greater than or less.

But let's spend a few minutes exploring the other common comparison operations.

The first four will probably be quite familiar to you from childhood math class,

and the last two may be new to you.

I'm back in my math ops project,

by the way, which is what we use to practice our arithmetical operations.

I'll just comment out the old code so it doesn't get in the way.

And then I'll give us some space down here, and I'll also

paste in the operations will be working on just do we have them for reference.

But I'll put those in the comment too.

But don't worry, we'll go through them one by one.

Earlier, I mentioned that comparisons don't return numerical results but

rather a yes or no.

Which means, we're gonna need a particular type of variable to handle the result.

And I hope that before I even finish that sentence, you were shouting bool

at your screen, since that's exactly what we're gonna need.

So, let's create a bool and we're gonna call it compareResult.

Now let's try some comparisons.

First we'll try greater than, for

which we can simply type compareResult = 5>3.

To translate that from computer to human, we're saying is five greater than three?

If true, set compare result to yes.

If not set compare result to no.

We can put a break point right here, Command + R, to run our code.

And, if we mouse over, we see compare

result is true, 5 is greater than 3.

Now let's try flipping our symbol.

I also actually like some space in here, so

I'm gonna put a space, and then that, I find that easier to read.

Let's run our code again, command + R.

We mouse over compare result false, 5 is definitely not less than 3.

We can take that result a step further and change our expression to a less than or

equal to.

Simply by adding an equals sign.

This can look a little funny.

But it actually makes sense.

You just read it less than or equal to.

We'll run that again.

Mouse over compareResult, false.

Five is definitely not less than or equal to three.

If we flip our operator.

To greater than or equal to three and run it again, we see we get true.

Five most definitely is greater than three.

Now just for kicks, let's change our three to a five and run it again.

Indeed we got true because 5 = 5.

Just to be sure, let's change this 5 to a 50, and we'll switch the sign.

False.

50 is neither less than nor equal to 5.

Okay, we got four down, and two to go.

Next, we have the double equal sign, which may look a little confusing at first,

sorta like a typo.

But in actuality, it's pretty simple.

So to do that, let's erase what we have here and we'll say 5 == 5.

Remember, the double equal sign is comparing two numbers, and

then determining if they're equal or not.

Remember, a single equals sign assigns a value.

It's called the assignment operator.

A double equals sign, like we have here, compares two values for equality.

Let's run this.

True, 5 does equal 5.

Now let's change it a bit.

False, 5 does not equal 5.75.

Okay, last up the not equal operator.

As you might guess, this decides if two values are not equal and if so,

returns yes.

This is written simply as an exclamation point followed by an equal sign.

If we run that, we'll see that we get true,

5 is not equal to 5.75.

In English, we could read this whole line as, is 5 not equal to 5.75?

If so, return true.

If not, return false.

In our case, it's gonna return true, because these two numbers are not equal.

By the way, that exclamation mark is often referred to as a bang in programming.

That's this exclamation mark right here.

Though unlike clever jargon, like camelcase or

breadcrumb, the slang wasn't created or popularized by programmers.

In actuality, it was popularized by the female secretaries of the 1950s,

who often used the term bang when typing in shorthand.

Hopefully much of what we just learned seemed familiar or

at least intuitive to you.

But if not, don't despair.

Using comparison operators like less than or equal to is something you'll get

plenty of practice with as we work through more and more code examples.

That said, if you feel like you need a good cheat sheet on hand,

I've linked one in the teacher's notes.