---
title: "Implementing the Init Function in a Move Module"
description: "In this tutorial, we'll explore the Init function in a Move module and learn how to implement it. The Init function is a special function that is executed…"
last_updated: 2026-08-21
---

# Implementing the Init Function in a Move Module

In this tutorial, we'll explore the Init function in a Move module and learn how to implement it. The Init function is a special function that is executed only once when the associated module is published. It has a specific signature and takes only one argument.

1. Understanding the Init function:

The Init function is defined with the following signature:

```rust
fun init(ctx: &mut TxContext) { /* ... */ }
```

2. Creating a Move module with the Init function:

Let's create a Move module called "one_timer" and implement the Init function within it. In this example, we'll create a `CreatorCapability` struct and ensure that only the module's author has a version of it.

Start by creating a new Move file (e.g., "one_timer.move") and add the following code to define the module:

```rust
module examples::one_timer {
    // Import required modules and types
    use sui::transfer;
    use sui::object::{Self, UID};
    use sui::tx_context::{Self, TxContext};

    // Define the CreatorCapability struct
    struct CreatorCapability has key {
        id: UID
    }

    // Implement the Init function
    fun init(ctx: &mut TxContext) {
        // Your code here
    }
}
```

3. Implementing the Init function:

Inside the `init` function, we'll create an instance of the `CreatorCapability` struct and transfer it to the module's author. Add the following code to the `init` function:

```rust
transfer::transfer(CreatorCapability {
    id: object::new(ctx),
}, tx_context::sender(ctx))
```

4. Final Move module with Init function:

After adding the `init` function implementation, your complete "one_timer.move" module should look like this:

```rust
module examples::one_timer {
    use sui::transfer;
    use sui::object::{Self, UID};
    use sui::tx_context::{Self, TxContext};

    /// The one of a kind - created in the module initializer.
    struct CreatorCapability has key {
        id: UID
    }

    /// This function is only called once on module publish.
    /// Use it to make sure something has happened only once, like
    /// here - only module author will own a version of a
    /// `CreatorCapability` struct.
    fun init(ctx: &mut TxContext) {
        transfer::transfer(CreatorCapability {
            id: object::new(ctx),
        }, tx_context::sender(ctx))
    }
}
```

Save the file, and you've successfully implemented the Init function in a Move module. This ensures that the `CreatorCapability` struct is only created once and assigned to the module's author when the module is published.

## Is Init Function in move like main function in other language?

The `init` function in Move is not equivalent to the `main` function in other programming languages. While both serve as entry points for execution, their purposes and behaviors are different:

1. Purpose: The `main` function in many programming languages is the primary entry point for the execution of a program, responsible for initializing and running the application. In contrast, the `init` function in Move is a special function that is executed only once when a module is published. Its primary purpose is to perform one-time setup or initialization tasks for the module, such as creating resources or initializing state.

2. Frequency of execution: The `main` function is executed every time the program is run, whereas the `init` function in Move is executed only once when the module is published, and never again during the module's lifetime.

3. Return values: In most programming languages, the `main` function can have a return value, typically used to indicate the success or failure of the program's execution. However, the `init` function in Move typically does not have a return value, as its purpose is to perform one-time setup tasks.

4. Access: The `main` function is often a global entry point for a program, whereas the `init` function is local to the Move module in which it is defined. The `init` function cannot be called explicitly by other modules or transactions.

In summary, while both the `main` function and the `init` function serve as entry points for execution, their roles, behaviors, and use cases differ significantly due to the unique requirements of the Move programming language and smart contracts. The `init` function is more focused on module setup and initialization, while the `main` function is responsible for running a program.