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pragma solidity ^0.4.11;
/**
* Math operations with safety checks
*/
library SafeMath {
function mul(uint a, uint b) internal returns (uint) {
uint c = a * b;
assert(a == 0 || c / a == b);
return c;
}
function div(uint a, uint b) internal returns (uint) {
// assert(b > 0); // Solidity automatically throws when dividing by 0
uint c = a / b;
// assert(a == b * c + a % b); // There is no case in which this doesn't hold
return c;
}
function sub(uint a, uint b) internal returns (uint) {
assert(b <= a);
return a - b;
}
function add(uint a, uint b) internal returns (uint) {
uint c = a + b;
assert(c >= a);
return c;
}
function max64(uint64 a, uint64 b) internal constant returns (uint64) {
return a >= b ? a : b;
}
function min64(uint64 a, uint64 b) internal constant returns (uint64) {
return a < b ? a : b;
}
function max256(uint256 a, uint256 b) internal constant returns (uint256) {
return a >= b ? a : b;
}
function min256(uint256 a, uint256 b) internal constant returns (uint256) {
return a < b ? a : b;
}
function assert(bool assertion) internal {
if (!assertion) {
throw;
}
}
}
/**
* @title ERC20Basic
* @dev Simpler version of ERC20 interface
* @dev see https://github.com/ethereum/EIPs/issues/20
*/
contract ERC20Basic {
uint public totalSupply;
function balanceOf(address who) constant returns (uint);
function transfer(address to, uint value);
event Transfer(address indexed from, address indexed to, uint value);
}
/**
* @title ERC20 interface
* @dev see https://github.com/ethereum/EIPs/issues/20
*/
contract ERC20 is ERC20Basic {
function allowance(address owner, address spender) constant returns (uint);
function transferFrom(address from, address to, uint value);
function approve(address spender, uint value);
event Approval(address indexed owner, address indexed spender, uint value);
}
/**
* @title Basic token
* @dev Basic version of StandardToken, with no allowances.
*/
contract BasicToken is ERC20Basic {
using SafeMath for uint;
mapping(address => uint) balances;
/**
* @dev Fix for the ERC20 short address attack.
*/
modifier onlyPayloadSize(uint size) {
if(msg.data.length < size + 4) {
throw;
}
_;
}
/**
* @dev transfer token for a specified address
* @param _to The address to transfer to.
* @param _value The amount to be transferred.
*/
function transfer(address _to, uint _value) onlyPayloadSize(2 * 32) {
balances[msg.sender] = balances[msg.sender].sub(_value);
balances[_to] = balances[_to].add(_value);
Transfer(msg.sender, _to, _value);
}
/**
* @dev Gets the balance of the specified address.
* @param _owner The address to query the the balance of.
* @return An uint representing the amount owned by the passed address.
*/
function balanceOf(address _owner) constant returns (uint balance) {
return balances[_owner];
}
}
/**
* @title Standard ERC20 token
*
* @dev Implemantation of the basic standart token.
* @dev https://github.com/ethereum/EIPs/issues/20
* @dev Based on code by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
*/
contract StandardToken is BasicToken, ERC20 {
mapping (address => mapping (address => uint)) allowed;
/**
* @dev Transfer tokens from one address to another
* @param _from address The address which you want to send tokens from
* @param _to address The address which you want to transfer to
* @param _value uint the amout of tokens to be transfered
*/
function transferFrom(address _from, address _to, uint _value) onlyPayloadSize(3 * 32) {
var _allowance = allowed[_from][msg.sender];
// Check is not needed because sub(_allowance, _value) will already throw if this condition is not met
// if (_value > _allowance) throw;
balances[_to] = balances[_to].add(_value);
balances[_from] = balances[_from].sub(_value);
allowed[_from][msg.sender] = _allowance.sub(_value);
Transfer(_from, _to, _value);
}
/**
* @dev Aprove the passed address to spend the specified amount of tokens on beahlf of msg.sender.
* @param _spender The address which will spend the funds.
* @param _value The amount of tokens to be spent.
*/
function approve(address _spender, uint _value) {
// To change the approve amount you first have to reduce the addresses`
// allowance to zero by calling `approve(_spender, 0)` if it is not
// already 0 to mitigate the race condition described here:
// https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
if ((_value != 0) && (allowed[msg.sender][_spender] != 0)) throw;
allowed[msg.sender][_spender] = _value;
Approval(msg.sender, _spender, _value);
}
/**
* @dev Function to check the amount of tokens than an owner allowed to a spender.
* @param _owner address The address which owns the funds.
* @param _spender address The address which will spend the funds.
* @return A uint specifing the amount of tokens still avaible for the spender.
*/
function allowance(address _owner, address _spender) constant returns (uint remaining) {
return allowed[_owner][_spender];
}
}
/**
* @title VTrust ERC20 token
*
* @dev Implemantation of the VTrust token.
*/
contract VTrust is StandardToken {
string public name = "VTrust";
string public symbol = "VTR";
uint public decimals = 6;
uint public INITIAL_SUPPLY = 1000000000000000; // Initial supply is 1,000,000,000 VTR
function VTrust() {
totalSupply = INITIAL_SUPPLY;
balances[msg.sender] = INITIAL_SUPPLY;
}
}
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