🔮
Ethereum
  • General
    • What is Ethereum
      • Ethereum & Bitcoin General Comparison
      • Singleton State
      • The Ethereum Virtual Machine (EVM)
      • Opcodes (operation codes) EVM
      • Ethereum Client
      • Forks
      • Gas (wei)
        • EIP-1559
        • Table Conversion (wei)
      • Proof of Stake (PoS)
      • Proof of Authority (PoA)
      • The Beacon Chain
      • Networks
        • Ethereum mainnet
        • Goerli
      • Account-based model & UTXO-based model
      • Externally Owned Account (EOA)
      • Node Clients
        • Geth
        • Nethermind
      • Contract Account
      • Smart Contract Upgradeability
      • Ultrasound Money
      • Merkle Trees
        • Patricia Merkle Tree
      • Tries
        • State Trie
        • Storage Trie
        • Transactions Trie
        • Receipts Trie
      • Transactions
        • Ethereum Transaction Architecture
      • World State
        • Chain of States
        • Chain of Blocks
        • Stack of Transactions / Mempool
      • Contract Creation
      • Message Call Transaction
      • P2P Network
      • Web3.js
      • Ether.js
        • Smart Contract Interaction Example
      • Web3.js vs Ether.js
      • Node Providers
      • ENS (Ethereum Name Service)
      • Web3 dapp
      • Escrow
      • Multi-signature
      • ERC-20 tokens
        • Send ERC20s to Contracts
      • NFTs
        • ERC-721 and ERC-1155
      • Solidity
        • State Variables
        • Data Location
        • Numbers
        • Modifiers
        • View & Pure Modifiers
        • Data Types
          • Modifiers
          • Modifiers (Functions)
          • Address & Address Payable
        • Hardhat
        • Payable Functions
        • Receive Function
        • Fallback Function
        • Global Variables
        • Self Destruct
        • Create2 Function
        • Revert function
        • Require function
        • Assert Function
        • Calldata
        • Interface
        • Mapping
        • Array
        • Struct
        • Inheritance
          • Virtual & Overwrite
          • Multiple inheritance
          • Hierarchical Inheritance
        • Events
          • Indexed (keyword)
          • LOG0 - LOG4
        • Multi-signature Example
        • Smart Contracts
          • Context
      • Application Binary Interface (ABI )
  • Extras
    • Terminology
      • Bytecode
      • Keccak-256
      • Turing complete
Powered by GitBook
On this page
  1. General
  2. What is Ethereum
  3. Solidity

Require function

PreviousRevert functionNextAssert Function

Last updated 2 years ago

In Solidity, require is a function used to check a certain condition and revert the transaction if it evaluates to false. It can be used to verify inputs, pre-conditions, and other conditions that must hold for a function to execute successfully. If a require statement fails, all changes to the state are rolled back and the remaining gas is refunded. Here's an example:

function buy(uint256 amount) public payable {
    require(msg.value == amount * price, "Incorrect payment amount.");
    // ... rest of the function
}

In the example above, the require statement checks if the value sent in the transaction is equal to the required amount, and if not, it reverts the transaction with the specified error message.

Expressions and Control Structures — Solidity 0.8.19 documentation
Logo