Created
November 13, 2017 02:56
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Created using browser-solidity: Realtime Ethereum Contract Compiler and Runtime. Load this file by pasting this gists URL or ID at https://ethereum.github.io/browser-solidity/#version=soljson-v0.4.18+commit.9cf6e910.js&optimize=false&gist=
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pragma solidity ^0.4.16; | |
interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) public; } | |
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; | |
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 | |
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 | |
Burn(_from, _value); | |
return true; | |
} | |
} | |
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