**The final standard can be found here: https://eips.ethereum.org/EIPS/eip-20**

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The final standard can be found here: https://eips.ethereum.org/EIPS/eip-20

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ERC: 20
Title: Token standard
Status: Draft
Type: Informational
Created: 19-11.2015
Resolution: https://github.com/ethereum/wiki/wiki/Standardized_Contract_APIs

Abstract

The following describes standard functions a token contract can implement.

Motivation

Those will allow dapps and wallets to handle tokens across multiple interfaces/dapps.

The most important here are, transfer, balanceOf and the Transfer event.

Specification

Token

Methods

NOTE: An important point is that callers should handle false from returns (bool success). Callers should not assume that false is never returned!

totalSupply

function totalSupply() constant returns (uint256 totalSupply)

Get the total token supply

balanceOf

function balanceOf(address _owner) constant returns (uint256 balance)

Get the account balance of another account with address _owner

transfer

function transfer(address _to, uint256 _value) returns (bool success)

Send _value amount of tokens to address _to

transferFrom

function transferFrom(address _from, address _to, uint256 _value) returns (bool success)

Send _value amount of tokens from address _from to address _to

The transferFrom method is used for a withdraw workflow, allowing contracts to send tokens on your behalf, for example to "deposit" to a contract address and/or to charge fees in sub-currencies; the command should fail unless the _from account has deliberately authorized the sender of the message via some mechanism; we propose these standardized APIs for approval:

approve

function approve(address _spender, uint256 _value) returns (bool success)

Allow _spender to withdraw from your account, multiple times, up to the _value amount. If this function is called again it overwrites the current allowance with _value.

allowance

function allowance(address _owner, address _spender) constant returns (uint256 remaining)

Returns the amount which _spender is still allowed to withdraw from _owner

Events

Transfer

event Transfer(address indexed _from, address indexed _to, uint256 _value)

Triggered when tokens are transferred.

Approval

event Approval(address indexed _owner, address indexed _spender, uint256 _value)

Triggered whenever approve(address _spender, uint256 _value) is called.

History

Historical links related to this standard:

• Original proposal from Vitalik Buterin: https://github.com/ethereum/wiki/wiki/Standardized_Contract_APIs/499c882f3ec123537fc2fccd57eaa29e6032fe4a
• Reddit discussion: https://www.reddit.com/r/ethereum/comments/3n8fkn/lets_talk_about_the_coin_standard/

最初由 @frozeman 在 https://github.com/ethereum/EIPs/issues/20 发布