이더리움 토큰 만들기

기본 contract 작성

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pragma solidity ^0.4.20;

contract MyToken {
event Transfer(address indexed from, address indexed to, uint256 value);
/* This creates an array with all balances */
mapping (address => uint256) public balanceOf;
string public name;
string public symbol;
uint8 public decimals;
/* Initializes contract with initial supply tokens to the creator of the contract */
function MyToken(uint256 initialSupply, string tokenName, string tokenSymbol, uint8 decimalUnits) public {
balanceOf[msg.sender] = initialSupply; // Give the creator all initial tokens
name = tokenName; // Set the name for display purposes
symbol = tokenSymbol; // Set the symbol for display purposes
decimals = decimalUnits; // Amount of decimals for display purposes
}

/* Send coins */
function transfer(address _to, uint256 _value) public {
require(balanceOf[msg.sender] >= _value); // Check if the sender has enough
require(balanceOf[_to] + _value >= balanceOf[_to]); // Check for overflows
balanceOf[msg.sender] -= _value; // Subtract from the sender
balanceOf[_to] += _value; // Add the same to the recipient
/* Notify anyone listening that this transfer took place */
emit Transfer(msg.sender, _to, _value);
}
}

상속을 이용한 보다 심플란 contract 작성하기

is owned를 통해 상속을 하여 owner 변수와 onlyOwner modifier에 접근할 수 있게 되었다.

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pragma solidity ^0.4.20;

contract owned {
address public owner;

function owned() {
owner = msg.sender;
}

modifier onlyOwner {
require(msg.sender == owner);
_;
}

function transferOwnership(address newOwner) onlyOwner {
owner = newOwner;
}
}

contract MyToken is owned{
event Transfer(address indexed from, address indexed to, uint256 value);
/* This creates an array with all balances */
mapping (address => uint256) public balanceOf;
string public name;
string public symbol;
uint8 public decimals;
/* Initializes contract with initial supply tokens to the creator of the contract */
function MyToken(
uint256 initialSupply,
string tokenName,
uint8 decimalUnits,
string tokenSymbol,
address centralMinter
) {
if(centralMinter != 0 ) owner = centralMinter;
}

/* Send coins */
function transfer(address _to, uint256 _value) public {
require(balanceOf[msg.sender] >= _value); // Check if the sender has enough
require(balanceOf[_to] + _value >= balanceOf[_to]); // Check for overflows
balanceOf[msg.sender] -= _value; // Subtract from the sender
balanceOf[_to] += _value; // Add the same to the recipient
/* Notify anyone listening that this transfer took place */
emit Transfer(msg.sender, _to, _value);
}
}

#

향상된 최종 코인

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pragma solidity ^0.4.16;

contract owned {
address public owner;

function owned() public {
owner = msg.sender;
}

modifier onlyOwner {
require(msg.sender == owner);
_;
}

function transferOwnership(address newOwner) onlyOwner public {
owner = newOwner;
}
}

interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) external; }

contract TokenERC20 {
// Public variables of the token
string public name;
string public symbol;
uint8 public decimals = 18;
// 18 decimals is the strongly suggested default, avoid changing it
uint256 public totalSupply;

// This creates an array with all balances
mapping (address => uint256) public balanceOf;
mapping (address => mapping (address => uint256)) public allowance;

// This generates a public event on the blockchain that will notify clients
event Transfer(address indexed from, address indexed to, uint256 value);

// This notifies clients about the amount burnt
event Burn(address indexed from, uint256 value);

/**
* Constrctor function
*
* Initializes contract with initial supply tokens to the creator of the contract
*/
function TokenERC20(
uint256 initialSupply,
string tokenName,
string tokenSymbol
) public {
totalSupply = initialSupply * 10 ** uint256(decimals); // Update total supply with the decimal amount
balanceOf[msg.sender] = totalSupply; // Give the creator all initial tokens
name = tokenName; // Set the name for display purposes
symbol = tokenSymbol; // Set the symbol for display purposes
}

/**
* Internal transfer, only can be called by this contract
*/
function _transfer(address _from, address _to, uint _value) internal {
// Prevent transfer to 0x0 address. Use burn() instead
require(_to != 0x0);
// Check if the sender has enough
require(balanceOf[_from] >= _value);
// Check for overflows
require(balanceOf[_to] + _value > balanceOf[_to]);
// Save this for an assertion in the future
uint previousBalances = balanceOf[_from] + balanceOf[_to];
// Subtract from the sender
balanceOf[_from] -= _value;
// Add the same to the recipient
balanceOf[_to] += _value;
emit Transfer(_from, _to, _value);
// Asserts are used to use static analysis to find bugs in your code. They should never fail
assert(balanceOf[_from] + balanceOf[_to] == previousBalances);
}

/**
* Transfer tokens
*
* Send `_value` tokens to `_to` from your account
*
* @param _to The address of the recipient
* @param _value the amount to send
*/
function transfer(address _to, uint256 _value) public {
_transfer(msg.sender, _to, _value);
}

/**
* Transfer tokens from other address
*
* Send `_value` tokens to `_to` in behalf of `_from`
*
* @param _from The address of the sender
* @param _to The address of the recipient
* @param _value the amount to send
*/
function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
require(_value <= allowance[_from][msg.sender]); // Check allowance
allowance[_from][msg.sender] -= _value;
_transfer(_from, _to, _value);
return true;
}

/**
* Set allowance for other address
*
* Allows `_spender` to spend no more than `_value` tokens in your behalf
*
* @param _spender The address authorized to spend
* @param _value the max amount they can spend
*/
function approve(address _spender, uint256 _value) public
returns (bool success) {
allowance[msg.sender][_spender] = _value;
return true;
}

/**
* Set allowance for other address and notify
*
* Allows `_spender` to spend no more than `_value` tokens in your behalf, and then ping the contract about it
*
* @param _spender The address authorized to spend
* @param _value the max amount they can spend
* @param _extraData some extra information to send to the approved contract
*/
function approveAndCall(address _spender, uint256 _value, bytes _extraData)
public
returns (bool success) {
tokenRecipient spender = tokenRecipient(_spender);
if (approve(_spender, _value)) {
spender.receiveApproval(msg.sender, _value, this, _extraData);
return true;
}
}

/**
* Destroy tokens
*
* Remove `_value` tokens from the system irreversibly
*
* @param _value the amount of money to burn
*/
function burn(uint256 _value) public returns (bool success) {
require(balanceOf[msg.sender] >= _value); // Check if the sender has enough
balanceOf[msg.sender] -= _value; // Subtract from the sender
totalSupply -= _value; // Updates totalSupply
emit Burn(msg.sender, _value);
return true;
}

/**
* Destroy tokens from other account
*
* Remove `_value` tokens from the system irreversibly on behalf of `_from`.
*
* @param _from the address of the sender
* @param _value the amount of money to burn
*/
function burnFrom(address _from, uint256 _value) public returns (bool success) {
require(balanceOf[_from] >= _value); // Check if the targeted balance is enough
require(_value <= allowance[_from][msg.sender]); // Check allowance
balanceOf[_from] -= _value; // Subtract from the targeted balance
allowance[_from][msg.sender] -= _value; // Subtract from the sender's allowance
totalSupply -= _value; // Update totalSupply
emit Burn(_from, _value);
return true;
}
}

/******************************************/
/* ADVANCED TOKEN STARTS HERE */
/******************************************/

contract MyAdvancedToken is owned, TokenERC20 {

uint256 public sellPrice;
uint256 public buyPrice;

mapping (address => bool) public frozenAccount;

/* This generates a public event on the blockchain that will notify clients */
event FrozenFunds(address target, bool frozen);

/* Initializes contract with initial supply tokens to the creator of the contract */
function MyAdvancedToken(
uint256 initialSupply,
string tokenName,
string tokenSymbol
) TokenERC20(initialSupply, tokenName, tokenSymbol) public {}

/* Internal transfer, only can be called by this contract */
function _transfer(address _from, address _to, uint _value) internal {
require (_to != 0x0); // Prevent transfer to 0x0 address. Use burn() instead
require (balanceOf[_from] >= _value); // Check if the sender has enough
require (balanceOf[_to] + _value >= balanceOf[_to]); // Check for overflows
require(!frozenAccount[_from]); // Check if sender is frozen
require(!frozenAccount[_to]); // Check if recipient is frozen
balanceOf[_from] -= _value; // Subtract from the sender
balanceOf[_to] += _value; // Add the same to the recipient
emit Transfer(_from, _to, _value);
}

/// @notice Create `mintedAmount` tokens and send it to `target`
/// @param target Address to receive the tokens
/// @param mintedAmount the amount of tokens it will receive
function mintToken(address target, uint256 mintedAmount) onlyOwner public {
balanceOf[target] += mintedAmount;
totalSupply += mintedAmount;
emit Transfer(0, this, mintedAmount);
emit Transfer(this, target, mintedAmount);
}

/// @notice `freeze? Prevent | Allow` `target` from sending & receiving tokens
/// @param target Address to be frozen
/// @param freeze either to freeze it or not
function freezeAccount(address target, bool freeze) onlyOwner public {
frozenAccount[target] = freeze;
emit FrozenFunds(target, freeze);
}

/// @notice Allow users to buy tokens for `newBuyPrice` eth and sell tokens for `newSellPrice` eth
/// @param newSellPrice Price the users can sell to the contract
/// @param newBuyPrice Price users can buy from the contract
function setPrices(uint256 newSellPrice, uint256 newBuyPrice) onlyOwner public {
sellPrice = newSellPrice;
buyPrice = newBuyPrice;
}

/// @notice Buy tokens from contract by sending ether
function buy() payable public {
uint amount = msg.value / buyPrice; // calculates the amount
_transfer(this, msg.sender, amount); // makes the transfers
}

/// @notice Sell `amount` tokens to contract
/// @param amount amount of tokens to be sold
function sell(uint256 amount) public {
require(address(this).balance >= amount * sellPrice); // checks if the contract has enough ether to buy
_transfer(msg.sender, this, amount); // makes the transfers
msg.sender.transfer(amount * sellPrice); // sends ether to the seller. It's important to do this last to avoid recursion attacks
}
}
논어에서 배우다 03 이더리움 Greeter 만들기

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