Cairo by example

structs

A struct is a collection of named fields. It is one of the ways to define custom user types.

The fields of a struct, called members, can be of any defined type.

For example:

struct Employee {
    age: u8,
    id: u32,
    role: felt252, // String
}

Struct members can be user-defined types:

struct Company {
    employees: Vec<Employee>,
    number_of_buildings: u32
}

You can instantiate structs via the following syntax:

let employee = Employee {
    age: 53,
    id: 1616,
    role: 'engineer',
};

If you have variables named the same as the members, you can use a shorter syntax:

let age = 53;
let id = 1616;
let role = 'engineer';

let employee = Employee {
    age,
    id,
    role,
};

The full example:

use array::ArrayTrait;

#[derive(Copy, Drop)]
struct Employee {
    age: u8,
    id: u32,
    role: felt252,
}

#[derive(Drop)]
struct Company {
    employees: Array<Employee>,
    number_of_buildings: u32
}

fn main() {
    let employee = Employee {
        age: 53,
        id: 1616,
        role: 'engineer',
    };
    let mut employees = ArrayTrait::new();
    employees.append(employee);

    let number_of_buildings = 53;

    let company = Company {
        number_of_buildings,
        employees,
    };
}

Try it out!

Install the toolchain:

For macOS and Linux, run our script:

curl -sL https://raw.githubusercontent.com/lambdaclass/cairo-by-example/main/build/installer.sh | bash -s 2.2.0

For Windows and others, please see the official guide

Run the example:
1. Copy the example into a structs.cairo file and run with:

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