WEBVTT

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Conditional programming or branching is something you do every day, every moment.

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It's about evaluating conditions if the light is red.

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Then I can cross.

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If I'm hungry, I need to eat.

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And if I'm late for work, then I will call my boss.

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And the main tool is the if statement, which comes in different forms and colors.

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But its basic function is to evaluate an expression and based on the result, choose which part of the

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code to execute.

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As usual, let's look at this example here.

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So if I am Am is late here and true here true.

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And after that we will.

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If is late is true, then print.

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I need I need to get.

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I need to call my boss.

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And this is possible.

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The simplest example.

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So when fed to if statement the is late acts as a conditional expression which is evaluated in a boolean

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context.

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And remember that is late here.

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This is late variable here is boolean, not a string.

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Not.

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Value tuple or anything.

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It is a boolean.

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It's another primitive type.

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Boolean.

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You will learn about that in next lectures also.

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So.

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Uh, so Boolean also can Boolean has two values, either false or true.

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So if the result of the evaluation is true, then we enter the body of the code immediately after the

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if statement.

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Notice that the print instruction is indented, which means that it belongs to scope defined by the

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if here.

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And that's because this is indentation here.

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So if we run this code, as you can see, I need to call my boss.

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If we make it is late.

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False.

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So we are not late for now.

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And as you can see, we didn't evaluate anything.

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So this code is didn't work or didn't need it to work here.

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So depending on the result of evaluating the late is late expression, we can either enter block one

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or block two, but not both.

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So block one is executed when late evaluates to true while block two here is executed when the late

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evaluates to false.

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So try and assigning false and true to this is late too.

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To see how the output of this code changes accordingly.

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So in this example also introduced the else clause in which becomes very handy when we want to provide

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an alternative set of instructions to be executed.

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When an expression evaluates to false within an if class.

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So the class is optional, as is evident by comparing preceding two examples.

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And in with these examples we will do in next lecture.

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So I'm waiting you in.

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Next lecture.