Working with struct and enum

There are several elementary types in solidity that can be used together to form various complex user-defined types. In this recipe, you will learn about two user-defined types in Solidity: struct and enum.

How to do it...

Let's create and work with various user-defined types using struct and enum.

Structs 

Structs provide a way to define new types of solidity:

1. Use the struct keyword for creating user-defined types in solidity:

struct Person { }

2. Create a struct with a name and the associated properties inside it:

struct Person {
    uint16 id;
    bytes32 fName;
    bytes32 lName;
}

3. Structs can also include arrays, mapping, or other user-defined types:

struct Person {
    uint16 id;
    bytes32 fName;
    bytes32 lName;
    Contact phone;
}

struct Contact {
    uint countryCode;
    uint number;
}

4. You cannot create a struct member with its own type. This helps in limiting the size of the struct to a finite value.

5. Create a variable of the struct type as follows:

Person owner...