Getting Started with Solidity

Tutorial 1 of 5

Introduction

This tutorial aims to provide a solid foundation for getting started with Solidity, the main programming language for Ethereum Smart Contract development. By the end of this tutorial, you will understand the basic syntax of Solidity, key concepts, and how to write your first smart contract.

Prerequisites

Basic understanding of Blockchain and Ethereum
Knowledge of JavaScript or a similar programming language would be helpful

Step-by-Step Guide

Solidity Basics

Solidity is statically typed, supports inheritance, and complex user-defined types which makes it possible to create complex contracts that are still easy to manage.

Here is a basic example of a Solidity contract:

pragma solidity ^0.4.0;

contract SimpleContract {
    function doSomething() public {
    }
}

In the example above, pragma solidity ^0.4.0; specifies the compiler version. contract SimpleContract { } is the contract declaration, and function doSomething() public { } is a public function declaration.

Writing Your First Contract

Let's write a simple contract that stores a value and includes a function to change it.

pragma solidity ^0.4.0;

contract SimpleStorage {
    uint storedData;

    function set(uint x) public {
        storedData = x;
    }

    function get() public view returns (uint) {
        return storedData;
    }
}

In this contract, we declare a state variable storedData of type uint. The set function changes the value of the variable and the get function returns the current value. The public keyword makes the function callable from outside the contract.

Code Examples

Here's an example of a more complex contract, a basic voting contract:

pragma solidity ^0.4.0;

contract Voting {
    // Model a Candidate
    struct Candidate {
        uint id;
        string name;
        uint voteCount;
    }

    // Store Candidates
    // Fetch Candidate
    mapping(uint => Candidate) public candidates;

    // Store Candidates Count
    uint public candidatesCount;

    // Constructor
    constructor () public {
        addCandidate("Candidate 1");
        addCandidate("Candidate 2");
    }

    function addCandidate (string _name) private {
        candidatesCount ++;
        candidates[candidatesCount] = Candidate(candidatesCount, _name, 0);
    }
}

In this contract, we have a struct to model a candidate with an id, name, and voteCount. We then have a mapping that stores candidates. The constructor function is called when the contract is deployed and adds two candidates to the contract.

Summary

In this tutorial, you've learned the basics of Solidity and how to write simple contracts. You're encouraged to experiment with the examples provided and try to extend them.

Next Steps

For further learning, you might want to explore topics such as contract inheritance, complex data types like arrays and enums, and how to interact with contracts using web3.js.

Additional Resources

Practice Exercises

Create a contract that allows users to set and get a string message.
Extend the Voting contract to allow voting and ensure that a voter can only vote once.
Write a contract that simulates a simple auction.

Remember, practicing is key to mastering Solidity. Happy coding!