14 Day Beginner Challenge (SwiftUI) - Lesson 12 Strange Behavior

General Discussion
1

Hello everyone! I just have a question regarding my code for the War Card Game in which the game behaves somewhat inconsistently.

To illustrate:

The game behaves as normal during the first 3 instances. The player’s card is larger than the CPU’s card and so it increases the value of the player’s score.

Screen Shot 2021-10-01 at 1.33.37 PM
Screen Shot 2021-10-01 at 1.33.37 PM1920×1223 82.4 KB

However, as you can see in this instance - the player’s card is clearly larger than the CPU’s card - however the CPU’s score is increased instead of the player

Why is this the case? What did I do wrong? I realize that Chris used “playerRand” and “cpuRand” for his if statements, whereas I used “playerCard” and “cpuCard” - however, I do not understand why this wouldn’t work logically. Can someone please explain?

import SwiftUI

struct ContentView: View {

@State var playerCard = "card5"
@State var cpuCard = "card9"
@State var playerScore = 0
@State var cpuScore = 0


var body: some View {
    
    ZStack{
        Image("background").ignoresSafeArea()
        
        VStack{
            Spacer()
            Image("logo")
            Spacer()
            
            HStack{
                Spacer()
                Image(playerCard)
                Spacer()
                Image(cpuCard)
                Spacer()
            }
            
            Spacer()
            
            Button(action: {
                
                //Generate a random number between 2 and 14
                let playerRand = Int.random (in: 2...14)
                let cpuRand = Int.random(in: 2...14)
                
                //Update the cards
                playerCard = "card" + String(playerRand)
                cpuCard = "card" + String(cpuRand)
                
                
                //Update the score
                if playerCard > cpuCard {
                    
                    playerScore += 1
                }
                
                else if cpuCard > playerCard {
                    
                    cpuScore += 1
                }
                
                
                
            }) {Image("dealbutton")}
           
            Spacer()
            
            HStack{
                Spacer()
                VStack{
                    Text("Player")
                        .foregroundColor(Color.white)
                        .font(.largeTitle)
                        .padding()
                    Text(String(playerScore))
                        .foregroundColor(Color.white)
                        .font(.title)
                }
                
                Spacer()
                VStack{
                    Text("CPU")
                        .foregroundColor(Color.white)
                        .font(.largeTitle)
                        .padding()
                    Text(String(cpuScore))
                        .foregroundColor(Color.white)
                        .font(.title)
                }
                Spacer()
                
            }
        Spacer()
        }
        
    }
    
}

}

struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}

2

In this line, you are comparing strings.

The string “card11” (i.e., a Jack) is not greater than the string “card4” because strings are not compared the same as integers.

let playerInt = 11
let cpuInt = 4
print(playerInt > cpuInt)
//prints true

let playerCard = "card11"
let cpuCard = "card4"
print(playerCard > cpuCard)
//prints false

With integers, 11 is obviously greater than 4.

With strings, you aren’t workinng with the numbers 11 and 4, you are working with the characters "11" and "4". Since the character "1" sorts before the character "4", then "11" comes first. Numbers (like Ints) are sorted numerically; strings are sorted lexicographically.

Run this code in a playground and you will see what I mean:

let rng = 1...14

//sorted range of Ints
print(rng.sorted())
//prints [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14]

//sorted range of strings
print(rng.map { "\($0)" }.sorted())
//prints ["1", "10", "11", "12", "13", "14", "2", "3", "4", "5", "6", "7", "8", "9"]
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3

Correct, so you should be comparing cpuRand to playerRand, as Chris did (now you know why).

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