Enums.md

31 - Enums

They can be used to create custom types with a finite set of constant values to improve readability.

They need a minimum of one member and can have a maximum of 256.

They can be explicitly converted to/from integers.

The options are represented by unsigned integer values starting from 0.

The default value is the first member.

---

Slide Screenshot

---

Slide Deck

• User-defined Type
• Finite Set -> Constant Values
• Min: 1, Max: 256
• Improves Readability

---

References

• Youtube Reference
• Solidity by Example - Enums

---

Solidity by Example

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.3;

contract Enum {
    // Enum representing shipping status
    enum Status {
        Pending,
        Shipped,
        Accepted,
        Rejected,
        Canceled
    }

    // Default value is the first element listed in
    // definition of the type, in this case "Pending"
    Status public status;

    // Returns uint
    // Pending  - 0
    // Shipped  - 1
    // Accepted - 2
    // Rejected - 3
    // Canceled - 4
    function get() public view returns (Status) {
        return status;
    }

    // Update status by passing uint into input
    function set(Status _status) public {
        status = _status;
    }

    // You can update to a specific enum like this
    function cancel() public {
        status = Status.Canceled;
    }

    // delete resets the enum to its first value, 0
    function reset() public {
        delete status;
    }
}

---

Tags

Enums Cont.