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How to create variables during a project execution

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CA

CodeBuilder_Alex

Posted on May 18, 2020 • Beginner

🔧 Need help with creating variables during project execution

Hey everyone! I’m working on a multiplayer game where players can join at any time. I want to create variables dynamically to track each player’s position:

  • Store each player’s X coordinate
  • Store each player’s Y coordinate
  • Use their username as part of the variable name

Is it possible to create new variables while the project is running? I’m thinking about cloud variables but not sure how to approach this. Any guidance would be super helpful! 🙏

VS

VariableSpecialist_Sam

Replied 3 hours later • ⭐ Best Answer

Great question @CodeBuilder_Alex! This is a common misconception about Scratch variables. Let me clarify how variables work and provide some practical solutions:

🚫 The Reality About Dynamic Variable Creation

You cannot create new variables during project execution. Variables must be created before the project starts running. However, there are several effective workarounds!

flowchart TD A[🚀 Project Start] --> B[Pre-created Variables Available] B --> C[Player Joins Game] C --> D{Variable Assignment Strategy} D -->|Option 1| E[Use Lists for Multiple Players] D -->|Option 2| F[Use Cloud Variables with Encoding] D -->|Option 3| G[Pre-create Player Slots] E --> H[📝 Add to Player List] F --> I[☁️ Encode Data in Cloud Variable] G --> J[🎯 Assign to Available Slot] H --> K[Update Position Data] I --> K J --> K K --> L{More Players Join?} L -->|Yes| C L -->|No| M[🎮 Continue Game] style A fill:#e1f5fe style B fill:#f3e5f5 style E fill:#e8f5e8 style F fill:#fff3e0 style G fill:#fce4ec

💡 Solution 1: Using Lists (Recommended)

The best approach is to use lists to store player data dynamically:

    when flag clicked
delete all of [Player Names v]
delete all of [Player X v]
delete all of [Player Y v]

// When a new player joins
when I receive [player joined v]
add (username) to [Player Names v]
add (x position) to [Player X v]
add (y position) to [Player Y v]

☁️ Solution 2: Cloud Variables with Data Encoding

For multiplayer games, you can encode multiple player data in cloud variables:

    // Encode player data as: username:x:y,username2:x2:y2
when I receive [update player data v]
set [☁ player data v] to (join (join (join (username) [:]) (join (x position) [:])) (join (y position) [,]))

// To read player data
set [player info v] to (☁ player data)
// Parse the string to extract individual player positions

🎯 Solution 3: Pre-created Player Slots

Create variables for a maximum number of players beforehand:

    // Pre-create variables: Player1_X, Player1_Y, Player2_X, Player2_Y, etc.
when I receive [assign player slot v]
if <(Player1_Name) = []> then
set [Player1_Name v] to (username)
set [Player1_X v] to (x position)
set [Player1_Y v] to (y position)
else
if <(Player2_Name) = []> then
set [Player2_Name v] to (username)
set [Player2_X v] to (x position)
set [Player2_Y v] to (y position)
end
end

🔧 Best Practices

  • Use Lists: Most flexible for unknown number of players
  • Cloud Variables: Great for persistent multiplayer data
  • Pre-planning: Always design your variable structure before coding
  • Data Management: Clean up unused slots when players leave

Hope this helps clarify how to handle dynamic player data in Scratch! 😊

CA

CodeBuilder_Alex

Replied 45 minutes later

@VariableSpecialist_Sam This is exactly what I needed! Thank you so much! 🎉

The list approach makes perfect sense. I was overthinking the variable creation part. One follow-up question - how do I efficiently find a specific player’s data in the lists?

LS

ListSearcher_Maya

Replied 1 hour later

@CodeBuilder_Alex Great follow-up question! Here’s how to efficiently search for player data:

    // Custom block: find player index
define find player (player name)
set [player index v] to [0]
repeat (length of [Player Names v])
change [player index v] by [1]
if <(item (player index) of [Player Names v]) = (player name)> then
// Found the player! Use 'player index' to get their data
set [found player x v] to (item (player index) of [Player X v])
set [found player y v] to (item (player index) of [Player Y v])
stop [this script v]
end
end
set [player index v] to [0] // Player not found

This way you can quickly locate any player’s position data! 🔍

VB

Vibelf_Community

Pinned Message • Moderator

🚀 Master Advanced Variable Management!

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  • 🗃️ Complex data structures
  • 🔄 Real-time multiplayer synchronization
  • 💾 Persistent data storage
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