What are the Best Solidity Smart Contract Examples?

The growth of blockchain technology has invited attention to many significant advancements. Cryptocurrencies made their presence felt in the financial markets worldwide, and blockchain technology made headlines everywhere. Was blockchain limited to cryptocurrencies only? No, different blockchain platforms were working on their unique and innovative offerings. 

Any smart contract code example can help you understand how smart contract functionality changed the blockchain landscape permanently. Developers can leverage smart contracts to come up with complex applications that follow the decentralized approach. Solidity is one of the most popular programming languages for creating smart contracts, especially for Ethereum. Interestingly, Solidity ensures that smart contract functionality is universally available. Let us learn about different examples of Solidity smart contract code and their significance.

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Why Should You Learn the Examples of Solidity Smart Contracts?

You must be wondering why you must learn the examples of smart contracts in Solidity. The best reason to learn Solidity smart contract examples is the power that Ethereum holds over the blockchain industry. Ethereum was the first blockchain to introduce smart contract programmability with the help of Solidity.

Programming smart contracts on Ethereum was not as easy as it is now because only a few programmers were fluent in the EVM architecture. Solidity emerged as a promising solution to help developers in the construction of decentralized applications. The first version of Solidity was launched in 2021 and has been serving as a major force for transformation of smart contract development experience for users. 

Solidity helped in solving many problems associated with smart contract development, such as compatibility and scalability. The best Solidity smart contract examples can show you how Solidity has reduced the overall difficulty in smart contract development process. Smart contract development with conventional programming languages was a clumsy and complex process.

Solidity served as the next big solution for simplification of smart contract development. It has removed complexity by ensuring a direct association of its syntax and structure with EVM. Solidity ensures translation of written code to EVM codes, thereby ensuring better convenience for developers.

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Discovering the Components of Smart Contract Code in Solidity

The importance of Solidity for smart contract development provides a clear impression of the reasons for its popularity. You must be curious about queries like “How do you write a smart contract in Solidity?” after learning the importance of Solidity. The code of Solidity has to be encapsulated in contracts.

Smart contracts or contracts in Solidity include a collection of code or its relevant functions and data or its relevant state, residing at a particular address on Ethereum blockchain. Contracts serve as fundamental blocks for application development on Ethereum. Here are two examples of Solidity smart contract codes that can give you a basic idea of how they work and the components in Solidity code. 

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Basic Solidity Smart Contract 

The best Solidity contract example to start with is a simple example like the ‘helloWorld’ examples for other programming languages. Here’s what a simple, smart contract looks like in Solidity.

pragma solidity ^0.5.0;

 
contract firstContract {

 function helloWorld () public pure returns (string) {

   return "HelloWorld !. This is your first Contract";

 }

}

The code example features one method, “helloWorld ().” The method returns the “HelloWorld !. This is your first Contract” string as the output.

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Solidity Smart Contract with set () and get () Functions

Another notable addition among the top Solidity smart contract examples is the smart contract, in which you can use the set () and get () functions. The following example uses the set () function to set the value of the state variable in the smart contract. On the other hand, the get () function can help in obtaining the set value from the contract.

// SPDX-License-Identifier: GPL-3.0 

pragma solidity >= 0.4.16 < 0.9.0;

contract Storage

{

       uint public setData;

     function set(uint x) public

    {

        setData = x;

    }

     function get(

    ) public view returns (uint) {

        return setData;

    }

}

Let us break down this smart contract code example to understand how you can also create a contract with Solidity. Here are the important components that you must note in the contract code example.

• Version Pragma

pragma solidity >=0.4.16 <0.9.0;

The smart contract code starts with pragmas, which serve as instructions for the compiler on how it must treat the code. Every Solidity source code must begin with the ‘version pragma’ that officially declares the version of Solidity compiler it would use. The use of version pragma in this Solidity contract example proves its functionality in any Solidity contract code. It helps prevent any compatibility issues with the future versions of the compiler that may feature some changes. In this example, you can notice that the code is compatible with compilers with a version more than 0.4.16 and less than 0.9.0 version.

• Contract Keyword

The ‘contract Storage { }’ component of the code draws attention to the contract keyword. It serves a valuable role in declaring a contract that would encapsulate the code. 

• State Variables

Another common highlight in answers to “How do you write a smart contract in Solidity?” draws attention to state variables. In this example, you can notice state variables in the line,

uint public setData;

State variables are permanent additions to the contract storage and are written directly to the Ethereum blockchain. The concerned line in the code example provides a declaration of a state variable “setData” with the type ‘uint’ or an unsigned integer of 256 bits. You can think of the line as a method for addition of slots in a database. 

• Function Declaration 

The most crucial highlight in a smart contract code example is the function declaration, which looks like the following,

function set(uint x) public

function get() public view returns (uint)

You can notice these two functions at distinct parts of the smart contract code. First of all, you have a function ‘set,’ which has a public access modifier type. The function would take variable x of uint data type as the parameter. It can serve as an essential addition to a simple, smart contract for updating the value of “setData.” 

The function allows anyone to call and overwrite the value of “setData” stored in Ethereum blockchain without any barriers. Therefore, you would have a completely decentralized and censorship-resistant smart contract, which would be unaffected by centralized server shutdowns.

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What are the Other Solidity Contract Examples You Must Learn?

The simple example of Solidity contracts showcases the fundamentals you need to find your way through Solidity contract development. On the contrary, you can seek the top Solidity smart contract examples that cater to emerging requirements. The examples can not only help you understand the power of Solidity but also help you level up your game in Solidity programming. Here are some of the notable examples of Solidity smart contracts for different purposes.

ERC-20 Token Contract

ERC-20 token standard is a mandatory addition to the checklist of every aspiring Solidity developer. It helps in defining a specific set of rules for creation of fungible tokens. Here is an example of an ERC-20 token contract in Solidity.

contract ERC20Token {
    string public name;
    string public symbol;
    uint8 public decimals = 18;
    uint256 public totalSupply;

    mapping(address => uint256) public balanceOf;
    mapping(address => mapping(address => uint256)) public allowance;

    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);

    constructor(uint256 initialSupply, string memory tokenName, string memory tokenSymbol) {
        totalSupply = initialSupply * 10 ** uint256(decimals);
        balanceOf[msg.sender] = totalSupply;
        name = tokenName;
        symbol = tokenSymbol;
    }

    // Additional functions...
}

ERC-721 Token Contract 

The next addition among best Solidity smart contract examples would draw the limelight on ERC-721 tokens. You can use ERC-721 standard for creating NFTs. Here is an example of an ERC-721 token contract on Solidity.

contract ERC721Token {
    string public name;
    string public symbol;

    mapping(uint256 => address) public ownerOf;
    mapping(address => uint256) public balance;
    mapping(uint256 => address) public approved;

    event Transfer(address indexed from, address indexed to, uint256 tokenId);
    event Approval(address indexed owner, address indexed approved, uint256 tokenId);
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    function transferFrom(address from, address to, uint256 tokenId) external;
    function approve(address to, uint256 tokenId) external;
    
    // Additional functions...
}

General Auction Contract

You can also create online auctions on the blockchain with Solidity smart contracts. Developers can leverage a simple auction contract for this purpose. The contract can help bidders compete for items, and the highest bidder will win when the auction ends. Here is an example of a general auction contract you can create in Solidity.

contract SimpleAuction {
    address public beneficiary;
    uint256 public auctionEndTime;

    address public highestBidder;
    uint256 public highestBid;

    mapping(address => uint256) public pendingReturns;

    bool public ended;

    event HighestBidIncreased(address bidder, uint256 amount);
    event AuctionEnded(address winner, uint256 amount);

    constructor(uint256 _biddingTime, address _beneficiary) {
        beneficiary = _beneficiary;
        auctionEndTime = block.timestamp + _biddingTime;
    }

    function bid() public payable;
    function withdraw() public returns (bool);
    function auctionEnd() public;
    
    // Additional functions...
}

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Final Words

The review of Solidity smart contract examples reveals that it is a straightforward and simple programming language. You don’t have to be a programming expert to learn how Solidity works. On top of it, the diverse use cases of Solidity contracts present more favorable avenues for its adoption.

Solidity would serve as a major force in the web3 revolution by supporting the development of NFTs and dApps. You can also become a Solidity expert by starting your learning journey as soon as possible. Learn more about the fundamentals of Solidity and how you can extract the best results from it right away.

*Disclaimer: The article should not be taken as, and is not intended to provide any investment advice. Claims made in this article do not constitute investment advice and should not be taken as such. 101 Blockchains shall not be responsible for any loss sustained by any person who relies on this article. Do your own research!

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