ERC20 Standard Implementation

1. System Overview

The ERC20 standard implementation is a standard token contract implemented in Solidity that fully complies with the ERC20 standard interface specification. This implementation includes basic token functionality and extended features, along with necessary security mechanisms.

1.1 Main Features

Standard compliance: Fully compliant with ERC20 standard
Basic functions: Transfer, approval, query, and other basic operations
Extended features: Increase/decrease allowance and other extended operations
Event tracking: Complete event logging
Security checks: Comprehensive security validation
Precise calculation: Support for decimal configuration

2. Contract Implementation

solidity

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/utils/Context.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";

/**
 * @title ERC20 Token
 * @dev ERC20 standard token implementation
 */
contract ERC20 is Context {
    using SafeMath for uint256;

    // State variables
    string private _name;                   // Token name
    string private _symbol;                 // Token symbol
    uint8 private _decimals;               // Decimal places
    uint256 private _totalSupply;          // Total supply

    mapping(address => uint256) private _balances;                      // Account balances
    mapping(address => mapping(address => uint256)) private _allowances; // Allowance amounts

    // Events
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Constructor
     */
    constructor(
        string memory name_,
        string memory symbol_,
        uint8 decimals_,
        uint256 totalSupply_
    ) {
        require(bytes(name_).length > 0, "ERC20: name is empty");
        require(bytes(symbol_).length > 0, "ERC20: symbol is empty");
        
        _name = name_;
        _symbol = symbol_;
        _decimals = decimals_;
        
        // Initialize total supply
        _mint(_msgSender(), totalSupply_);
    }

    /**
     * @dev Get token name
     */
    function name() public view returns (string memory) {
        return _name;
    }

    /**
     * @dev Get token symbol
     */
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Get decimal places
     */
    function decimals() public view returns (uint8) {
        return _decimals;
    }

    /**
     * @dev Get total supply
     */
    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev Get account balance
     */
    function balanceOf(address account) public view returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev Get allowance amount
     */
    function allowance(address owner, address spender) public view returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev Transfer tokens
     */
    function transfer(address to, uint256 amount) public returns (bool) {
        address owner = _msgSender();
        _transfer(owner, to, amount);
        return true;
    }

    /**
     * @dev Approve allowance
     */
    function approve(address spender, uint256 amount) public returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, amount);
        return true;
    }

    /**
     * @dev Transfer tokens with allowance
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) public returns (bool) {
        address spender = _msgSender();
        _spendAllowance(from, spender, amount);
        _transfer(from, to, amount);
        return true;
    }

    /**
     * @dev Increase allowance amount
     */
    function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, _allowances[owner][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Decrease allowance amount
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
        address owner = _msgSender();
        uint256 currentAllowance = _allowances[owner][spender];
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(owner, spender, currentAllowance - subtractedValue);
        }
        return true;
    }

    /**
     * @dev Internal transfer function
     */
    function _transfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");

        uint256 fromBalance = _balances[from];
        require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[from] = fromBalance - amount;
            _balances[to] += amount;
        }

        emit Transfer(from, to, amount);
    }

    /**
     * @dev Internal mint function
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _totalSupply = _totalSupply.add(amount);
        unchecked {
            _balances[account] += amount;
        }
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Internal burn function
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        unchecked {
            _balances[account] = accountBalance - amount;
            _totalSupply -= amount;
        }

        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Internal approve function
     */
    function _approve(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Internal spend allowance function
     */
    function _spendAllowance(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        uint256 currentAllowance = allowance(owner, spender);
        if (currentAllowance != type(uint256).max) {
            require(currentAllowance >= amount, "ERC20: insufficient allowance");
            unchecked {
                _approve(owner, spender, currentAllowance - amount);
            }
        }
    }
}

3. Function Description

3.1 Basic Functions

Token information query: name, symbol, decimals, total supply
Account balance query: query token balance of specified account
Allowance query: query token allowance granted to specified account

3.2 Core Functions

Transfer: token transfer between accounts
Approve: authorize spending allowance
TransferFrom: transfer tokens with allowance

3.3 Extended Functions

Increase allowance: increase spending allowance
Decrease allowance: decrease spending allowance
Mint: create new tokens (internal)
Burn: destroy tokens (internal)

4. Security Mechanisms

4.1 Access Control

Zero address check
Balance verification
Allowance validation
Overflow protection

4.2 State Management

Balance tracking
Allowance tracking
Total supply management
Event logging

4.3 Error Handling

Requirement checks
Error messages
State rollback
Event notifications

5. Usage Examples

5.1 Deploy Token

javascript

const name = "My Token";
const symbol = "MTK";
const decimals = 18;
const totalSupply = ethers.utils.parseEther("1000000");
const token = await ERC20.deploy(name, symbol, decimals, totalSupply);

5.2 Transfer Tokens

javascript

const amount = ethers.utils.parseEther("100");
await token.transfer(recipient.address, amount);

5.3 Approve and TransferFrom

javascript

// Approve
const amount = ethers.utils.parseEther("50");
await token.approve(spender.address, amount);

// TransferFrom
await token.connect(spender).transferFrom(owner.address, recipient.address, amount);

6. Summary

The ERC20 standard implementation provides:

Complete standard compliance
Secure token operations
Extended functionality
Comprehensive error handling
Event tracking

Frequently Asked Questions (FAQ)

1. Basic Concepts

Q: What is ERC20? A: ERC20 is a token standard that defines:

Basic token functions
Event specifications
Interface requirements
State management
Security requirements

Q: Why use ERC20? A: Benefits include:

Wide compatibility
Standard interface
Proven security
Easy integration
Community support

Q: How to handle decimals? A: Decimal handling:

javascript

// Convert to token units
const amount = ethers.utils.parseUnits("100", decimals);

// Convert from token units
const humanReadable = ethers.utils.formatUnits(amount, decimals);

Q: How to manage allowances? A: Allowance management:

Use approve for initial setting
Use increaseAllowance for increases
Use decreaseAllowance for decreases
Check allowance before transfers

Q: What are common security risks? A: Main risks include:

Overflow/underflow
Unauthorized transfers
Allowance attacks
Reentrancy issues
Front-running attacks

Q: How to ensure transfer safety? A: Safety measures:

Balance checks
Address validation
SafeMath usage
Event logging
Access control

4. Best Practices

Q: What are deployment recommendations? A: Key considerations:

Initial supply planning
Decimal places selection
Permission settings
Testing verification
Audit completion

Q: How to optimize gas usage? A: Optimization strategies:

Batch operations
State caching
Gas limit settings
Code optimization
Event optimization

ERC20 Standard Implementation ​

1. System Overview ​

1.1 Main Features ​

2. Contract Implementation ​

3. Function Description ​

3.1 Basic Functions ​

3.2 Core Functions ​

3.3 Extended Functions ​

4. Security Mechanisms ​

4.1 Access Control ​

4.2 State Management ​

4.3 Error Handling ​

5. Usage Examples ​

5.1 Deploy Token ​

5.2 Transfer Tokens ​

5.3 Approve and TransferFrom ​

6. Summary ​

Frequently Asked Questions (FAQ) ​

1. Basic Concepts ​

2. Function-related ​

3. Security-related ​

4. Best Practices ​

ERC20 Standard Implementation

1. System Overview

1.1 Main Features

2. Contract Implementation

3. Function Description

3.1 Basic Functions

3.2 Core Functions

3.3 Extended Functions

4. Security Mechanisms

4.1 Access Control

4.2 State Management

4.3 Error Handling

5. Usage Examples

5.1 Deploy Token

5.2 Transfer Tokens

5.3 Approve and TransferFrom

6. Summary

Frequently Asked Questions (FAQ)

1. Basic Concepts

2. Function-related

3. Security-related

4. Best Practices