# Using the SDK

## Introduction

Randcast SDK is a set of smart contracts, libraries, scripts, and examples that can be used to build a DApp or Web3 game that requires randomness. The SDK is designed to be flexible and extensible. The SDK is written in Solidity and can be used in any EVM-compatible blockchain. It aims to help request randomness as well as consume randomness in a secure and easy way. In the next sections, we will introduce how to write a consumer contract, especially for implementing the callback functions.

We recommend using [Foundry](https://github.com/foundry-rs/foundry) to manage the dependencies, compile the project, run tests, and deploy.

## Installation

```bash
forge install ARPA-Network/Randcast-User-Contract
```

## Remapping Dependencies

You can customize these remappings by creating a `remappings.txt` file in the root of your project.

```
ds-test/=lib/forge-std/lib/ds-test/src/
forge-std/=lib/forge-std/src/
randcast-user-contract/=lib/Randcast-User-Contract/contracts/
```

## Usage

Now, we can import any of the contracts in `Randcast-User-Contract/contracts` like so:

```solidity
import {
    GeneralRandcastConsumerBase,
    BasicRandcastConsumerBase
} from "randcast-user-contract/user/GeneralRandcastConsumerBase.sol";
```

Users can focus on the business logic of their DApp or Web3 game by using the `GeneralRandcastConsumerBase`. This base contract provides a simple interface for requesting randomness and receiving results.

When requesting randomness, we provide three types of randomness: `Randomness`, `RandomWords`, and `Shuffling`.

For experienced developers, you can directly inherit the `BasicRandcastConsumerBase` contract to leverage a more flexible interface for requesting randomness. You can use this contract to request randomness in any way you want. See `AdvancedGetShuffledArrayExample` for an example.

***WARNING:** You **MUST** restrict access to the function that requests randomness in your consumer contract. Otherwise, anyone can call this function and use your subscription to pay for randomness requests.*

## Examples

See [consumer-contract-examples](https://docs.arpanetwork.io/randcast/using-the-sdk/consumer-contract-examples "mention") for more details.