Simple Introduction to Solidity｜Lecture 31: ERC20

Original title: " A minimalist introduction to Solidity: 31. ERC20 " 

Original author: 0xAA   

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This way , we will introduce the ERC20 Token standard on Ethereum and issue our own test Token .

ERC20

ERC20 is on Ethereum Token Standard, from EIP20 in November 2015 V God participated. it achieved Token The basic logic of circulation:

Account Balance

Transfer

Authorization

Token Total Inflow

Token Optional information (): name, code, decimal exposure 

IERC20

IERC20 is ERC20 Token A standard interface contract that specifies the ERC20 Token Functions and events that need to be implemented.

Event

IERC20 defines one and two events, respectively when the event is authorized and authorized Released TransferApproval

function

IERC20 defines 6 functions that provide a transfer Token , and approved for basic use on other chains.

totalSupply() returns Token Total Inflow  

balanceOf() returns account balance  

transfer( ) Shift  

allowance() returns the authorized amount  

approve() authorization  

transferFrom() license  
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Implement ERC20

Now write an ERC20, specifying the functions that our IERC20 can simply implement.

State variables

We need to record the account balance through state variables, including authorization and amount for Token type, automatically generates balanceOf a function of the same name, implementing the specified, and . . allowancetotalSupplypublicgetterIERC20balanceOf()allowance()totalSupply()namesymboldecimals

function

constructor: initialization Token name, code.   

transfer() function The transfer function in IERC20, Token accomplish. The caller's amount coin will increase Token Quantity, the receiver's corresponding dog reform, join, dividends, lottery, etc.   

approve() function: the approve function of IERC20, Token Authorization logic. The authorized party spender can control the amount of the authorized party Token .   

transferFrom() Function: transferFrom function in IERC20, authorization logic. The authorized party realizes the amount of the sender by the authorizing party Token Authorization to the recipient recipient.   

mint() function: Mint Token function, not in the IERC20 standard. Here for convenience, anyone can add any number of Token , rights management will be used in practical applications, only owner can be cast Token :  

burn() function: Token function, not in the IERC20 standard.   

Issuing ERC20 Token

Standard ERC20, issued on the ETH chain is now our easiest Token , we issue our first Token .

In the compiled ERC20 contract on Remix, enter the parameters of the constructor in the deployment column, name_ and symbol_ are set to WTF, and then click the transact button to deploy.

Deployment contract

WTF we need to run the mint() function to mint ourselves some Token . Click on the contract ERC20 in Deployed Contract, enter in the mint function column and click 100 mint to create such a 100 token WTF for yourself.

casting Token

Use our balanceOf() function to query the account balance. Enter the current account, you can check our balance 100, success.

balance inquiry

Summary

On this day, We studied the implementation of the ERC20 standard on Ethereum and released our test Token . ERC20 proposed at the end of 2015 Token Standards greatly reduce issuance on Ethereum Token threshold, and opened the ICO when investing, you can carefully read the project's Token The contract can effectively avoid bravery and increase the success rate of investment.

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