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Simple Counter

In this guide you will write one of the simplest smart contracts possible and learn how to deploy and interact with it. We will store just one integer value inside of it and increment it:

contracts/Incrementer.sol
// SPDX-License-Identifier: MIT
pragma solidity 0.8;

contract Incrementer {
    uint counter;

    constructor(uint startValue) {
        counter = startValue;
    }

    function increment() public {
        counter = counter + 1;
    }

    function getCounter() public view returns (uint) {
        return counter;
    }
}

To deploy it to the Aurora Testnet you need to follow the steps below.

tip

You can find the code of the whole project in GitHub repository.

Create project​

Open your favorite terminal application and clone the repo:

git clone git@github.com:aurora-is-near/aurora-examples.git
cd hardhat/incrementer-example

Configure project​

Add your Aurora Private key (from MetaMask or other Web3 wallet) to __.env__ file:

$ echo "AURORA_PRIVATE_KEY=YOUR_AURORA_PRIVATE_KEY_HERE" >> .env

Interact with contract​

note

To use the commands below you will need Node.js and yarn to be installed. Please follow the instructions here to install Node.js. Then, install yarn with npm install --global yarn or read more here.

To deploy the contract to Testnet run:

$ make deploy

Take the address of the deployed Incrementer from the output to use it in the next steps.

To get the current counter value run:

$ make get-counter INCREMENTER_ADDRESS=YOUR_INCREMENTER_ADDRESS_HERE

To increment the current counter value run:

$ make increment-counter INCREMENTER_ADDRESS=YOUR_INCREMENTER_ADDRESS_HERE

You can observe your transactions by using Aurora Block Explorer.

Switch a network​

Optionally you can specify any of the following networks for any command: testnet_aurora, mainnet_aurora, ropsten like this:

$ make deploy NETWORK=mainnet_aurora

More materials​

You can find a more detailed tutorial with a similar Incrementer example in the Getting Started with Aurora article.