Lesson 4: Practice Time!

Return to your magic potion code from the last exercise. You will want to run the healing code when the player drinks a healing potion, and the damage code when they drink a damaging potion.

First You Write Some Code ...

1. Sounds like you'll have to answer a question about the type of potion, so you can create a new variable to keep track of that, a string called PotionType.

   Verse

        var PotionType: string = "heal"
   

   Copy full snippet(1 line long)

2. Now you can ask if the variable PotionType is equal to another string. When you ask if PotionType is equal to "heal", the answer will be yes. The healing code would then run.

   Verse

        if (PotionType = "heal"):
            set PlayerHealth = PlayerHealth + PotionHealAmount
   

   Copy full snippet(2 lines long)

3. Now write a similar if expression for the damage code.

   Verse

        if (PotionType = "damage"):
            set PlayerHealth = PlayerHealth - PotionDamageAmount
   

   Copy full snippet(2 lines long)

   But wait! There’s a problem with the healing code!

   Nothing here stops a player from continuing to raise their health with potions. It’s a good idea to limit this, and now you can with if!

4. First, declare a new constant of type float. Call it MaxHealth and set it to 100.0.

   Verse

        MaxHealth: float = 100.0
   

   Copy full snippet(1 line long)

   If the value of PlayerHealth would go over the value of MaxHealth when a player drinks the healing potion, you'll need to set PlayerHealth to MaxHealth.

   Verse

    # Code to run if player drinks a healing potion
    # If the player's health would not exceed MaxHealth if they were healed,
    # heal them the full amount
    if (PotionType = "heal" and (PlayerHealth + PotionHealAmount) < MaxHealth):
        set PlayerHealth = PlayerHealth + PotionHealAmount
    else:
        set PlayerHealth = MaxHealth

   Copy full snippet(7 lines long)

   Notice that the code above has an and to ask if the PotionType is equal to "heal" and if the PlayerHealth + PotionAmount is less than MaxHealth. Both of these conditions need to succeed for the PlayerHealth to be increased by the PotionHealAmount.

   It may not be clear to someone reading this code that it’s meant to prevent PlayerHealth from exceeding MaxHealth. That’s where code comments come in. Note the three lines of comments above the actual code.

5. The damage code works, but it can be improved with the use of if … else if … else. If a player drinks a damage potion that would make PlayerHealth 0.0 or less, we want to set PlayerHealth to 1.0 instead. If PlayerHealth is already 1.0, then we set it to 0.0. This teaches the player the potion is harmful without being too punishing.

   Verse

        # Code to run if player drinks a damaging potion
        # Don't eliminate the player if their health is above MinHealth but below PotionDamageAmount
        # If they are already equal to or below MinHealth, eliminate them
        if (PotionType = "damage" and PlayerHealth > PotionDamageAmount):
            set PlayerHealth = PlayerHealth - PotionDamageAmount
        else if (PlayerHealth > MinHealth):
            # Give player one more chance if their health is low
            set PlayerHealth = 1.0
        else:
            set PlayerHealth = 0.0
   

   Copy full snippet(10 lines long)

... Then You Find the Bug

Below you’ll find all of the code from this exercise, with some Print() function calls added for testing. Try running this code. Feel free to change the Print() calls to whatever you like. With the PotionType variable initialized to “heal”, you can expect that only the healing code will run.

But wait, there’s a bug!

Run the code below and see if you can find it.

MaxHealth: float = 100.0
MinHealth: float = 1.0
var PotionType: string = "heal"

# Code to run if player drinks a healing potion
# If the player's health would not exceed MaxHealth if they were healed,
# heal them the full amount
if (PotionType = "heal" and (PlayerHealth + PotionHealAmount) < MaxHealth):
    set PlayerHealth = PlayerHealth + PotionHealAmount
    Print ("Full heal")

If PotionType is set to heal, only the healing code should run. However, the if … else if … if expressions in the damage code are still being executed. This means that if PlayerHealth is greater than MinHealth, the PlayerHealth will get set to 1.0. This is not what you want, but you can fix it by nesting the other checks within if expressions that only check PotionType.

# Code to run if player drinks a healing potion
# If the player's health would not exceed MaxHealth if they were healed,
# heal them the full amount
if (PotionType = "heal"):
    if ((PlayerHealth + PotionHealAmount) < MaxHealth):
        set PlayerHealth = PlayerHealth + PotionHealAmount
        Print ("Full heal")
    else:
        # set PlayerHealth the MaxHealth
        set PlayerHealth = MaxHealth

Now, only the block of code indented under one of the if expressions that check PotionType will run. Try this code with PotionType set to "damage" as well.

Whew! That’s a lot of code changes, but you did it!

Take a break, drink some po- er… water, and come back when you’re ready for the next lesson.

Complete Script

using { /Fortnite.com/Devices }
using { /Verse.org/Simulation }

hello_world_device := class(creative_device):

    # Runs when the device is started in a running game
    OnBegin<override>()<suspends> : void =

        MaxHealth : float = 100.0
        MinHealth : float = 1.0

Next Lesson

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  Lesson 5: Calling Functions

  Why do the same work twice if you don't have to?