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Lesson 11:
Enumerables
Introduction to enum types and how to use it in your smart contracts.
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Enumerables
Solidity supports enumerables(enum) and they are useful to keep track of state. Enums are one way to create a user-defined type.
The options are represented by subsequent unsigned integer values starting from 0.
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;
contract Game {
// Enum representing game status
enum Status {
NotStarted,
InProgress,
GameOver,
Won
}
// Default value is the first element listed in
// definition of the type, in this case "NotStarted"
Status public status;
// Returns uint
// NotStarted - 0
// InProgress - 1
// GameOver - 2
// Won - 3
function getStatus() public view returns (Status) {
return status;
}
// Update status by passing uint into input
function setStatus(Status _status) public {
status = _status;
}
// You can update to a specific enum like this
function win() public {
status = Status.Won;
}
// delete resets the enum to its first value, 0
function reset() public {
delete status;
}
}To declare enum:
pragma solidity ^0.8.24;
// This is saved as 'GameStatus.sol'
enum Status {
NotStarted,
InProgress,
GameOver,
Won
}To import the enum above:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;
import "./GameStatus.sol";
contract Enum {
Status public status;
function setStatus(Status _status) public {
status = _status;
}
}