ERC-20 Interface

ERC-20 is the standard interface for implementing fungible tokens on the Ethereum network. IERC20 defines the required functions and events that compliant contracts must implement. This interface is provided by OpenZeppelin, a widely-used, secure smart contract library.

Events

`Transfer`

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

Triggered when tokens are transferred from from to to.
value indicates the number of tokens transferred.
value can be zero.

`Approval`

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

Triggered when owner sets an allowance for spender.
value is the new approved amount.

Functions

`totalSupply`

 function totalSupply() external view returns (uint256);

Returns the total number of tokens in existence.

`balanceOf`

 function balanceOf(address account) external view returns (uint256);

Returns the number of tokens owned by account.

`transfer`

 function transfer(address to, uint256 value) external returns (bool);

Transfers value tokens from the caller to address to.
Returns true if successful.
Emits a Transfer event.

`allowance`

 function allowance(address owner, address spender) external view returns (uint256);

Returns the remaining number of tokens that spender is allowed to spend on behalf of owner.

`approve`

 function approve(address spender, uint256 value) external returns (bool);

Sets value as the allowance of spender over the caller's tokens.
Returns true if successful.
Emits an Approval event.

🔒 Note: Modifying allowances via approve() may lead to race conditions. A safer pattern is:

approve(spender, 0);
approve(spender, newValue);

`transferFrom`

function transferFrom(address from, address to, uint256 value) external returns (bool);

Transfers value tokens from from to to using the allowance mechanism.
The caller must have an allowance approved by from.
Returns true if successful.
Emits a Transfer event.

References

Based on OpenZeppelin v5.3
EIP-20 Specification: https://eips.ethereum.org/EIPS/eip-20
Recommended implementation: OpenZeppelin ERC20

This document provides a quick reference to the ERC-20 interface for developers implementing or interacting with ERC-20 tokens. For full functionality and customization, refer to actual implementation contracts.