Ethereum Virtual Machine (EVM) in Blockchain / Solidity

Introduction

The Ethereum Virtual Machine (EVM) is like a computer inside the Ethereum blockchain. It runs smart contracts, which are small programs that do tasks automatically.

When you want to create a program that runs on the Ethereum blockchain without needing a central server.

When you want to make a contract that automatically sends money or checks conditions.

When you want to build decentralized apps (dApps) that work the same for everyone.

When you want to ensure your code runs securely and cannot be changed once deployed.

When you want to interact with other smart contracts on Ethereum.

Syntax

Blockchain / Solidity

The EVM runs bytecode generated from high-level languages like Solidity.

Example of Solidity function compiled to EVM bytecode:

function add(uint a, uint b) public pure returns (uint) {
    return a + b;
}

The EVM itself does not use a traditional programming language but runs low-level bytecode.

Developers write smart contracts in languages like Solidity, which are then compiled to EVM bytecode.

Examples

This Solidity contract stores a number and lets you set or get it. It runs on the EVM.

Blockchain / Solidity

pragma solidity ^0.8.0;

contract SimpleStorage {
    uint storedData;

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

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

This contract has a function to add two numbers. The EVM executes this logic when called.

Blockchain / Solidity

pragma solidity ^0.8.0;

contract Adder {
    function add(uint a, uint b) public pure returns (uint) {
        return a + b;
    }
}

Sample Program

This contract keeps a count number. You can increase it by calling increment(), and check it with getCount(). The EVM runs this code on the blockchain.

Blockchain / Solidity

pragma solidity ^0.8.0;

contract Counter {
    uint public count = 0;

    function increment() public {
        count += 1;
    }

    function getCount() public view returns (uint) {
        return count;
    }
}

Important Notes

The EVM ensures all nodes on the Ethereum network run the same code and get the same results.

Gas is used to pay for running code on the EVM, so complex operations cost more.

Once a smart contract is deployed on the EVM, its code cannot be changed.

Summary

The EVM is a secure computer inside Ethereum that runs smart contracts.

Developers write contracts in Solidity, which the EVM executes as bytecode.

The EVM makes decentralized apps possible by running code the same way everywhere.