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In this video, we'll look at c++ relational operators.

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In addition to the equality operators, c++ also has several

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other relational or comparison operators.

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These are greater than, greater than or equal to,

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less than and less than or equal to.

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And in c++20, there'll be a really neat three-way comparison operator.

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This operator compares two expressions and evaluates to zero if they're equal,

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less than zero if the left-hand side is greater than the right-hand side

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and greater than zero if the right-hand side is greater than the left-hand side.

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Like the equality operators, these operators are very intuitive,

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easy to use and understand. Let's see a few examples in CodeLite.

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I'm in CodeLite. I'm in the section 8 workspace.

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And this is the relational operators project. In this project,

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I'm just using some really simple examples to test some of these

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relational operators.

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As you can see, I've got two numbers declared num1 and num2.

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This is where I'm going to read some integers into.

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And I'm asking the user to enter two integers separated by space

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and I'm reading those two integers from the user.

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Then what I'm doing in this output statement right here

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is suppose that the user entered 10 and 20 here.

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I'm just saying 10 greater than,

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I'm just explicitly printing out that greater than sign, 20

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and then I'm evaluating whether num1 is greater than num2 and that's going to say true or false.

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So it's going to do that for all four operators, greater than, greater than or equal to,

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less than and less than or equal to.

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And then we could try out a couple of examples with this program.

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So let's run it.

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And let's enter two integers. Okay. So let's enter 10 and 20.

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So you could see here, 10 greater than 20 is false.

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10 greater than or equal to 20 is false.

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10 less than 20 is true. And 10 less than or equal to 20 is also true.

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Okay. So now let's try some other ones,

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a couple of other test cases here. Let's try 20 and 20.

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In this case, you can see that 20 is greater -- 20 is not greater than 20.

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20 is, is greater than or equal to 20.

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20 is not less than 20. And 20 is less than or equal to 20.

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Just what we'd expect, so real simple example.

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What I'll do now is I'll comment out those output statements that we just did here.

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And I'll declare a couple of constants here.

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And I'll uncomment this piece of code out and I'll walk you through it.

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So in this case, I'm declaring two constants, lower and upper

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to be 10 and 20.

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And. I'm asking the user to enter an integer that's greater than lower.

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So in this case, I'm asking them to enter an integer that's greater than 10.

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And I left those as constants so you can modify them here and

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play around with this program yourself. So in this case, enter an integer that's greater than 10.

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I'm reading that integer into num1.

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Then I'm comparing to see if that number is greater than

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the lower limit which is 10 in this case.

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Then I'm doing the same thing. I'm saying enter an integer that's less than or equal to the upper limit.

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So let's run this.

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And first thing you'll see is it says enter --

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let me get rid of that

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statement at the beginning here.

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And we try that again.

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Here we go. So enter an integer that's greater than 10. So let's write 12.

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And it says 12 greater than 10 is true. That's what we expect.

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Now it says enter an integer that's less than or equal to 20.

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Let's put in 12. And it says 12

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less than or equal to 20 is true.

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Okay so let's run this one more time with a different test case.

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So enter an integer that's greater than 10. Let's put in 8 this time.

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And it says 8 greater than 10 is false. Obviously, I didn't do what i was told to do.

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And here enter an integer that's less than or equal to 20. Let's put in 25.

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And we can say 25 is less than or equal to 20 is also false.

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Okay. You can see where we're going with these operators.

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Once we get to control flow statements,

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you'll have all this knowledge under your belt

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and you'll really be able to write some really powerful programs that solve problems.