where to find the lesson list in devslopes

#WHERE TO FIND THE LESSON LIST IN DEVSLOPES CODE#

… comicBooks.remove(at: 2) print(unt) // Prints 5 Creating an empty array If we print unt below comicBooks.remove(at: 2) you should see that the count is back down to 5. In the above code, we wanted to remove the third comic book from our array, so we asked to remove the item at index 2. It may seem confusing, but that’s just the way it is. If you want the fourth value, you need to ask Swift for an index of 3. The second value has the identifier (or index) of 1, and so on.

In most programming languages, arrays use what is called zero-indexing meaning that the first value in our array is given an identifier of 0 to indicate the first value. So it worked, but if this is confusing it’s okay because this is where I will talk about zero-indexing. You should see the third value (1015.0) printed out on the right-hand side of the Playground. Wait a minute… Didn’t I just say to remove the third value from our array? Yes, and that is exactly what I did. comicBooks.append(500.0) print(unt) // Prints 6 because we added a new value! comicBooks.remove(at: 2) To remove the third value from our array, we need to add the following line of code: var comicBooks = print(unt) // Prints 5 because of total above. remove(at:) which allow us to remove a certain item at a certain point in our array. Pretty cool! What if you sold one of your comic books on eBay? How would we remove that item from the array? Removing an item from an arrayĪrrays in Swift include a function called. Try this: var comicBooks = print(unt) // Prints 5 because of total (500.0) print(unt) // Prints 6 because we added a new value! Just for explanation purposes, we are going to print the number of items in our array before we added our new $500 comic and after, too. For instance, we can calculate the total number of objects in our array. On the right-hand side of the Playground window, you should see the array print out, this time with a new value at the end - 500.0! Other things arrays can doĪrrays can do a couple cool things to help us manage a collection of data. To add is to our array, simply type: var comicBooks = comicBooks.append(500.0) After researching, you learn that it’s value is $500. With an array, it is easy to manage and modify our data.įor instance, let’s pretend that you scored and found an ultra-rare comic book at a garage sale. If we wanted to add a new comic book, we would have to add it at the end otherwise we would have messed up the number order of each variable. When we foolishly wrote the five variables above, it was difficult to manage and change. We could have also created it like this to explicitly set the type: var comicBookValues : = Appending an item to an array In the above example we have taken advantage of Swifts type inference to implicitly create an array of type Int. We’ve written an array of type Int and have filled the braces () with data.

#WHERE TO FIND THE LESSON LIST IN DEVSLOPES CODE#

Now we have a single line of code to replace the five lines we wrote above. Instead, we can create an Array called comicBooks and place the values inside of it like so: var comicBookValues = What if someone stole one of your comic books? What if you sold one? You would need to manually remove that line of code and then re-number the variables that follow it because each variable has a specific number and order. We could create a variable for each comic book and store the value like so: var comicBook1 = 10.0 var comicBook2 = 27.50 var comicBook3 = 1015.0 var comicBook4 = 55.0 var comicBook5 = 2.0 🤓 Imagine that you have a collection, albeit a small one, that includes 5 comic books. Let’s use one of the above examples: the value of each comic book in our collection.

You should see a screen like the one below.ĭelete all the boilerplate code on the left side but leave import UIKit as it is necessary. playground file and click Create to save it. Give it a name like “Arrays” and click Next. Setting up a Playgroundįirst, open Xcode if you haven’t already and click Create New Playground. In this chapter, we will see just how useful they can be. *cue triumphant music*!Īn array is an ordered collection that allow us to store multiple values. It is time and labor-intensive to create an individual variable for each of the above items and honestly it wouldn’t be good code. For example - employee salaries, the value of each comic book in our collection, or the cost per item in a store inventory. In the real world, we often need to keep track of multiple pieces of data that are all a part of the same category. The variables we learned about in chapter 3 are great for storing single values. It stores collections of data of multiple types and orders them numerically.

Where to find the lesson list in devslopes