Address Type

Move uses a special type called address to represent blockchain addresses. It is a 32-byte value capable of representing any address on the chain.

Addresses can be written in two forms:

• Hexadecimal addresses prefixed with 0x
• Named addresses defined in Move.toml

// address literal
let value: address = @0x1;

// named address registered in Move.toml
let value = @std;
let other = @stylus;

An address literal begins with the @ symbol followed by either a hexadecimal number or an identifier:

• The hexadecimal number is interpreted as a 32-byte value.
• The identifier is resolved in the Move.toml file and replaced with the corresponding address by the compiler.

If the identifier is not found in Move.toml, the compiler will throw an error.

Address Length

In EVM, the blockchain addresses are typically 20 bytes long. However, Move’s address type is 32 bytes long to ensure compatibility.

When working with EVM addresses in Move, it is common to use the lower 20 bytes of the 32-byte address type. The higher 12 bytes are usually set to zero.

For example, the UID types internally contains an address:

/// References a object ID
public struct ID has copy, drop, store {
    bytes: address,
}

/// Globally unique IDs that define an object's ID in storage. Any object, that is a struct
/// with the `key` ability, must have `id: UID` as its first field.
public struct UID has store {
    id: ID,
}

Since addresses are 32 bytes long, the UID type can represent any object ID in the Move storage system.

Warning

When interacting with EVM contracts, it is important to ensure that the addresses are correctly formatted and that only the lower 20 bytes are present.

i.e: let address: address = @0x1234567890abcdef1234567890abcdef12345678;