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Hey, guys.
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Welcome to another Swift Deep Dive.
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And in this Deep Dive, we're going to talk about functions that can have outputs.
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So far, we've already seen two types of functions.
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The most basic or the vanilla version if you will is simply where we package a bunch of code together
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and we execute them
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line by line in the same order.
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So that saves us from typing lots of code repeatedly, and especially when we have the functionality that
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needs to be executed multiple times.
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These types of functions can be really handy.
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Now, we also saw the upgraded version of the function, the strawberry flavor, where in addition to calling
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a function, we also were able to modify what the function did by providing an input.
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So for example, we could tell our robot how many bottles of milk to get, instead of it just executing
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the same road task every single time.
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Now, in this lesson, we're going to cover the third and, obviously, the most awesome type of functions, the
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chocolate flavor, which also happens to be my favorite.
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And in this third flavor, not only are we able to provide an input, namely how much money to give our
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robot, but we also get an output. In this case, it's a how much change the robot ends up with after buying
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our milk.
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So now we're talking about the type of functions that can actually have an output.
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Now, this is how we would create our function.
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We, again, have our func keyword, the name of our function, and we can if we want to have a set of parentheses
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where we provide our input and the data type of the input.
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Now, in order to specify that this function can produce an output, we add a return arrow here which is
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simply just a hyphen and a right angle bracket.
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And then, we add the data type that we expect to return, so the return type. And then we have a return
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keyword somewhere in the body of our function.
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And after the keyword is where we provide the value that will be the output of this function or the
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return value. And that value, of course, must match the return type that we specified earlier on.
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So when we call the function, this is what our code might look like.
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Unlike previously where we just had the function call, and then we just expected it to execute, well, in
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this case, we actually have an output. And this function call right here will actually become replaced
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by the output.
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So in this case, if we gave this function 4 as an input, 4 becomes the amount of money, 4 minus 2,
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the change becomes 2. The change that's returned or the output of this function is 2 which is, of course,
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a integer or a whole number data type.
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So this whole right-hand side of the equation becomes equal to 2 and that value gets assigned to our
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variable "change." Previously, we saw these two types of functions, a function that just has some code in
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it to be executed,
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and we called our function like so, which simply just does whatever is inside the curly braces.
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And we also had our functions with an input which can, of course, incorporate some piece of data into
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how it executes the code.
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So now it incorporates that and prints out the message depending on the input.
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Now, in our third type of function greeting3,
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well, now we might also have an input.
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Let's say it's a string data type, but we're also going to provide an output. And the output, in this case,
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I'm going to choose, is a boolean. Because what I want to do with my function is check to see if the input
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name,
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so the person at the door, let's imagine, has the name that matches somebody on my guest list, say, let's
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say, I'm only gonna allow "Angela" in, or if the name was equal to "Jack Bauer."
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So only Jack Bauer and Angela are allowed admittance.
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And in this case, if it did match, then we're going to return true which is, of course, a boolean data type,
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but otherwise, we're going to return false, so no entry.
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Now, when we call off function greeting3 and passing a name, let's say, my name,
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now this particular line, this part will be equal to the output. When the code runs,
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as you can see in the right-hand side of our Swift playground, it will be equal to whatever the output is which
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is, of course, true.
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Now, we can also capture this inside a variable. Let's say,
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doorShouldOpen, and we could set doorShouldOpen to the output of our greeting function.
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And now you can check and see that this doorShouldOpen has been assigned a boolean data type because
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the value that gets put in it is, of course, the output of our function greeting3.
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If you were to print doorsShouldOpen, then you will end up with the true value
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as long as this name is matching "Angela" or "Jack Bauer."
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But if it didn't, then we would end up with false.
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So this is our function; function with inputs and function with inputs and outputs.
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So now you're ready to tackle the assignment on Functions Part 3
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Part 3.