Chris Ching Course Part 4 (Challenges 1 and 2)

Right, here we go - time for the challenges! I'm going to take my time with these, look up the syntax in any previous blog entries - where necessary- and hope that they're not too hard! Right let's go!

Start time - 19:10

Challenge 1

Right I've listened to the first challenge instructions. As I mentioned before, there are a few ways of doing this - what I did last time worked well. I have to admit that I'm cheating a little, as I can pretty much see how this code plays out. But that's good - it means I'm remembering things and applying them!

// Challenge #1: The Lost Animal Challenge

//

// Instructions: 

// Given the two arrays below, write a function that takes a String as an input parameter and returns a Boolean value. The function should return true if the String input is in either array and it should return false if the String input is in neither array.

//

// Examples:

// Call your function and pass in the String "cat" as the input. Your function should return true

// Call your function and pass in the String "cow" as the input. Your function should return false

let array1 = ["dog", "cat", "bird", "pig"]

let array2 = ["turtle", "snake", "lizard", "shark"]

// Write your function below:

So the first thing to do before launching into the code is interpreting what the question is asking and what I must do.

Here's what I know for sure:

• I must have a function created
• It will take a string and return a bool
• The string input in either array returns true

So that is all fairly straight forward.

func animalFinder(animalName: String) -> Bool {

    

    let combinedArray = array1 + array2

    

    for animal in combinedArray {

        if animalName == animal {

            return true

        }

    }

    return false

}

I made an error here - I put in an else clause and had return false in a bracket before. Not totally sure why it needs to go in the next one down but I had to check with my previous attempt at this for the syntax and accidentally saw the answer! Last time I did this:

func stringFinder(_ animal: String) -> Bool {

    

    if array1.contains(animal) {

        return true

    } else if array2.contains(animal) {

        return true

    } else {

        return false

    }

    

}

Now I do like this original solution - I learned the 'contains' method by trying it out and it is pretty elegant. Still the original one cuts out a lot by combining the arrays. I could have done this...

func animalFinder2(animalName: String) -> Bool {

    

    if combinedArray.contains(animalName) {

    return true

    } else {

    return false

    }

}

So this works when I've moved 'combinedArray' outside of the scope, but I could have repeated the concatenating. Not sure if I actually need the else clause either!

So some good stuff here. Next!

Challenge 2

Challenge #2: The Caterpillar Challenge

//

// Instructions:

// Complete the class definition so that you get the expected output in the console (specified at the bottom of this playground).

//

// Each time the "add" function is called, keep track of the String input that is passed in.

//

// When the "go" function is called, use the print command to output all of the String data (added through calling the "add" function) on a single line.

//

// Example:

// See under the class definition for an example of expected output for the given commands.

// --- Your code goes below this line ---

class StringCaterpillar {

    

    var body = [String]()

    

    func add(_ text:String) {

        // Note:

        // You must use the body array declared above to store the pieces.

        // It may be unnecessary to use an array for this but my intention is for you to practice using arrays.

    }

    

    func go() {

        

    }

    

}

// --- Your code goes above this line ---

// --- Don't edit or add anything below this line ---

let myCaterpillar = StringCaterpillar()

myCaterpillar.add("h")

myCaterpillar.add("e")

myCaterpillar.add("l")

myCaterpillar.add("l")

myCaterpillar.add("o")

myCaterpillar.go()

// Expected Output:

// Expected output in the console after the above statements: "hello"

// For Bonus Credit: 

// Create a custom initializer so that you can declare a caterpillar object like this

//

// let myCaterpillar = StringCaterpillar("hi")

// 

// The input for this init should be stored.

//

// After changing the "myCaterpillar" constant above to use your new custom initializer, the new expected output should be: "hihello"

So there is a LOT to this one! First let's make sense of it...I was tempted to head straight in but that would have been silly!

Here is what we know...

• I need to add something to the add function
• I will be adding/creating/doing something with an array!
• When the add function is called, the character that is added is stored inside the body
• When go is called,  whatever string is now stored will be the output

Right so first of all let's focus on the add function. 

OK I think we could be done...

class StringCaterpillar {

    

    var body = [String]()

    

    func add(_ text:String) {

        body += [text]

      

    

    func go() {

        print(body)

        

    }

    

}

Xcode not running properly - AGAIN.... Is it that easy? Before I check, let's try the custom init...

convenience init(_: String) {

        self.init()

    }

Yes that seems to work!

OK, well I didn't quite get it but a good try! In the solution, Chris used the 'joined' method to put together the individual letters. 

Now here is what we have:

class StringCaterpillar {

    

    var body = [String]()

    

    init(_ startString: String) {

        body += [startString]

    }

    

    func add(_ text:String) {

        body += [text]

        

    }

    

    func go() {

        print(body.joined())

        

    }

     

}

A couple of points - I didn't need convenience init as there is only one! I've made it so you don't need to have a parameter to add in what you want to start with ("hi" from the example). I've learned the 'joined' method - that could be useful. So yes, although I didn't get it all, some useful stuff!

I also used += between the collection name and the item adding to it, rather than append. Absolutely fine!

I'm going to stop there!

Time - 19:59 (49 minutes total)

That's plenty for now. Some good stuff to have a look at in practice - lots of useful opportunities to apply some skills. This task was A LOT easier than when I looked it at it just a few days ago. So definitely worth doing! Next time it will be challenge 3, which looks like a real bugger!