SOLIDITY SMART CONTRACT

What is Ethereum?

Before getting started with smart contracts or Solidity let us first get an overview of what Ethereum is: Ethereum is a decentralized open-source blockchain with support for a Turing-complete programming language, Solidity. What we normally call computer programs are called smart contracts in Ethereum. Launched in 2015, Ethereum has been gaining significant popularity over the last 5 years. It is a permissionless, public blockchain, which means anyone can use the blockchain, though, for every write operation, you need to pay ETH (Gas).

What is a Smart Contract?

What is Solidity?

The steps this tutorial will go through:

• 1. Set up the project using NPM
• 2. Install the necessary dependencies
• 3. Make the project’s folder structure
• 4. Overview of the smart contract you’ll be writing
• 5. Writing the smart contract
• 6. Writing a javascript function that will compile & deploy the smart contract
• 7. Create an Alchemy account & Metamask wallet
• 8. Configure hardhat.config.js with alchemy
• 9. Deploy the smart contract
• 10. Conclusion/recap

1. Version Pragma:

pragma solidity >=0.4.16 < 0.7.0;
Pragmas are instructions to the compiler on how to treat the code. All solidity source code should start with a “version pragma” which is a declaration of the version of the solidity compiler this code should use. This helps the code from being incompatible with the future versions of the compiler which may bring changes. The above-mentioned code states that it is compatible with compilers of version greater than and equal to 0.4.16 but less than version 0.7.0.

2. The contract keyword:

contract Storage{
//Functions and Data
}
The contract keyword declares a contract under which the code is encapsulated.

3. State variables:

uint public setData;
State variables are permanently stored in contract storage, that is they are written in Ethereum Blockchain. The line uint setData declares a state variable called setData of type uint (unsigned integer of 256 bits). Think of it as adding a slot in a database.

4. A function declaration:

function set(uint x) public
function get() public view returns (uint)

This is a function named set of access modifier type public which takes a variable x of datatype uint as a parameter.

This was an example of a simple, smart contract that updates the value of setData. Anyone can call the function set and overwrite the value of setData, which is stored in the Ethereum blockchain and there is possibly no way for anyone to stop someone from using this function. This is an example of a decentralized application that is censorship proof and unaffected to the shutdown of any centralized server. As long as someone is running a single node of the Ethereum blockchain, this smart contract will be accessible.

Function get will retrieve and print the value of the state variable.

Output: