Before moving next to this article first visit this Hardhat setup development

Step 2

Creating the Solidity contract

The contracts directory will have the contract of your Hello World program. Delete the exsiting contracts/lock.sol file, create a HelloWorld.sol file in the contracts folder and write the following code.

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.4;

contract HelloWorld {
    //events
    //states
    //functions

    event messagechanged(string oldmsg, string newmsg);

    string public message;

    constructor(string memory firstmessage) {
        message = firstmessage;
    }

    function update(string memory newmesssage) public {
        string memory oldmsg = message;
        message = newmesssage;

        emit messagechanged(oldmsg, newmesssage);

    }
}

We start with the version of the solidity that we are using and then write the actual contract. A smart contract has states, functions and events.

• The states are usually variables, tokens, NFTs whose state we want to maintain in the contract.

• In order to read, write or change the states, we use functions.

• Events are triggers that are activated based on a transformation in a state, a call to a function etc. So our code right now has a state variable called message, a function called update and and event called messagechanged.

This is a basic HelloWorld code that takes a string when the smart contract is first time executed and if we want we can change that value to a new message as well.

Now that we have written the contract, the next step is to prepare for the deployment.