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The "Control Flow" Lesson is part of the full, Python Fundamentals course featured in this preview video. Here's what you'd learn in this lesson:

Nina demonstrates how to utilize control flow logic statements.


Transcript from the "Control Flow" Lesson

>> Nina Zakharenko: The if statement, the contents of the if statement will only run if the condition is true, otherwise they don't. So if 3 is less than 5,
>> Nina Zakharenko: We should see that printed out. If we do it the other way around,
>> Nina Zakharenko: If 3 is greater than 5,

>> Nina Zakharenko: We won't see anything. You don't need parentheses in your if statement here like you might in other languages, you just have to put a condition.
>> Nina Zakharenko: If statements also work with truthiness. So let's say a is an empty list and I say if a print("Hello"), what am I gonna see?

Nothing, right. What if I had a variable b, a list that had some items in it, and I say, if b print("Hello"), what will I see?
>> Speaker 2: You'll see it.
>> Nina Zakharenko: I'll see it, yeah, it's truthy. So,
>> Nina Zakharenko: If statements have a few more components to them. We know that the code in the if statement only runs if the if statement is true, right?

So I say a is true, if a print("Hello"). It'll run, right? If we want something to run in the opposite case, if a is not true, we'll say else, and use the colon and say Goodbye, right? So that prints out Hello if a was false, and we wrote the same code,

>> Nina Zakharenko: We'll get Goodbye.
>> Nina Zakharenko: One other thing here is else if. So let's say a is equal to true, and b is equal to true. So I can say, actually, sorry, let's make a false, and b true. So I can say, if a, right, if a is true, we're gonna print out 1.

Otherwise, I will say that with else if or in Python abbreviated to elif. Also with a colon, oops.
>> Nina Zakharenko: We need a condition here, and else if is not an else statement. So we'll check for something else. We'll say, elif b is true, print("2"). And then else means if neither of those conditions are met, print this other thing.

And you can have as many else ifs in your code as you want to. So in this case, it'll print out two. a was not true, so we skipped this. But this condition was true and so we went in here, and then we skipped the else because we found a condition that matched.

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