Hello World! in Solidity

Install

1. Install Node.js

   Download and install from the official site.

2. Install Truffle

   npm install -g truffle

Initialize

1. Initialize Truffle in your project folder

   truffle init

   After initialization, you will find two folders called contracts and migrations. Contracts go in the contracts folder while contract deployment settings go in migrations.

2. The "Hello World!" contract

   This is an example of a "Hello World!" contract in Solidity. "HelloWorld.sol" in contracts contains the following code:

   // SPDX-License-Identifier: MIT
   // compiler version must be greater than or equal to 0.8.17 and less than 0.9.0
   pragma solidity ^0.8.17;
   
   contract HelloWorld {
       string public greet = "Hello World!";
   }   

3. Prepare the migration

   "2_deploy_migration.js" in migrations contains the following code:

   var HelloWorld = artifacts.require("HelloWorld");
   module.exports = function(deployer) {
     deployer.deploy(HelloWorld);
   }

4. Start Truffle console in development mode

   truffle develop

   In the Truffle console, execute

   compile
   migrate

   If you want to remigrate existing contracts, run migrate --reset instead of simply migrate.

5. Test your contract

   In the interactive Truffle console, run the following commands:

   let instance = await HelloWorld.deployed()
   instance.greet()

   Then you will see:

   'Hello World!'