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pragma solidity ^0.4.0;
contract owned {
address public owner;
constructor() public {
owner = msg.sender;
}
modifier onlyOwner {
require(msg.sender == owner);
_;
}
function transferOwnership(address newOwner) onlyOwner public {
owner = newOwner;
}
}
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 token_balance; // NFO coin token balance on main net
mapping (address => uint256) public eth_balance; // associates Ethereum deposited on main net with main net addrress
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
*/
constructor (
uint256 initialSupply,
string tokenName,
string tokenSymbol
) public payable {
// Update total supply with the decimal amount
totalSupply = initialSupply * 10 ** uint256(decimals);
// Give the creator all initial tokens
token_balance[msg.sender] = totalSupply;
// initialize Ether balance of Fleet Coin contract
eth_balance[msg.sender] = msg.value;
// Set the name for display purposes
name = tokenName;
// Set the symbol for display purposes
symbol = tokenSymbol;
}
/**
* Internal transfer, only can be called by this contract
*/
function _transfer_token(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(token_balance[_from] >= _value);
// Check for overflows
require(token_balance[_to] + _value > token_balance[_to]);
// Save this for an assertion in the future
uint previousBalances = token_balance[_from] + token_balance[_to];
// Subtract from the sender
token_balance[_from] -= _value;
// Add the same to the recipient
token_balance[_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(token_balance[_from] + token_balance[_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_token(address _to, uint256 _value) public {
_transfer_token(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 transfer_token_from(address _from, address _to, uint256
_value) public returns (bool success) {
require(_value <= allowance[_from][msg.sender]); // Check allowance
allowance[_from][msg.sender] -= _value;
_transfer_token(_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
*/
/**
* 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(token_balance[msg.sender] >= _value); // Check if the sender has enough
token_balance[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(token_balance[_from] >= _value); // Check if the targeted balance is enough
require(_value <= allowance[_from][msg.sender]); // Check allowance
token_balance[_from] -= _value; // Subtractvfrom 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 orwell is owned, TokenERC20 {
/* This generates a public event on the blockchain that will notify clients */
event FrozenFunds(address target, bool frozen);
uint master_exchange_rate;
string[7] greetings;
/* Initializes contract with initial supply tokens to the creator of
the contract */
constructor (
uint256 initialSupply,
string tokenName,
string tokenSymbol
) TokenERC20(initialSupply, tokenName, tokenSymbol) public payable {
master_exchange_rate = 1000; // 1 ETH = 1000 FC
greetings[0] = "Hi, my name is Omar Metwally.";
greetings[1] = "I am the creator of this contract.";
greetings[2] = "To the future machine with the computational power to unlock today's encrypted secrets";
greetings[3] = "To the future human with the spiritual power to unlock all secrets.";
}
mapping(address => Chunk[]) public chunks;
mapping (address => bool) frozenAccount;
struct Chunk {
string text;
}
function new_chunk(string _text ) public payable returns (bool) {
chunks[msg.sender].push( Chunk( {
text: _text
}) );
eth_balance[msg.sender] += msg.value;
return true;
}
function get_num_chunks(address _owner) public view returns (uint) {
return chunks[_owner].length;
}
function update_chunk(uint _index, string _text ) public returns (bool) {
require( _index < chunks[msg.sender].length, "Invalid checkpoint address or index." );
chunks[msg.sender][_index].text = _text;
}
function get_chunk(address _owner, uint _index) public view returns( string _text ) {
require( _index < chunks[_owner].length, "Invalid index." );
Chunk storage ch = chunks[_owner][_index];
_text = ch.text;
}
function get_eth_balance(address eth_addr) public constant returns
(uint balance) {
return eth_balance[eth_addr];
}
function get_token_balance(address eth_addr) public constant returns
(uint balance) {
return token_balance[eth_addr];
}
/* 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 (token_balance[_from] >= _value); // Check if the sender has enough
require (token_balance[_to] + _value > token_balance[_to]); // Check for overflows
require(!frozenAccount[_from]); // Check if sender is frozen
require(!frozenAccount[_to]); // Check if recipient is frozen
token_balance[_from] -= _value; // Subtract from the sender
token_balance[_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 {
token_balance[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 Buy tokens from contract by sending ether
function buy() payable public {
uint amount = msg.value * master_exchange_rate; // buyPrice;
// calculates the amount
_transfer(owner, msg.sender, amount);
// makes the transfers
eth_balance[msg.sender] += msg.value;
// update eth_balance
token_balance[msg.sender] += amount; // update token_balance
}
/// @notice Sell `amount` tokens to contract
/// @param amount amount of tokens to be sold
function sell(uint256 amount) public {
require(eth_balance[this] >= (amount / master_exchange_rate) ); // checks if the contract has enough ether to buy
_transfer(msg.sender, owner, amount); // makes the transfers
msg.sender.transfer(amount / master_exchange_rate); // sends ether to the seller. It's important to do this last to avoid recursion attacks
token_balance[msg.sender] -= amount; // update token_balance
eth_balance[msg.sender] -= (amount/master_exchange_rate) ; // update eth_balance
}
function set_master_exchange_rate(uint new_rate) public returns (uint
exchange_rate) {
require(msg.sender == owner);
master_exchange_rate = new_rate;
return master_exchange_rate;
}
function greet_omar(uint _i) public constant returns (string greeting) {
require(_i>=0);
require(_i<greetings.length);
return greetings[_i];
}
}