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@vamshi4001 vamshi4001/ICO.sol
Created Sep 8, 2017

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pragma solidity ^0.4.11;
/**
* @title SafeMath
* @dev Math operations with safety checks that throw on error
*/
library SafeMath {
function mul(uint256 a, uint256 b) internal returns (uint256) {
uint256 c = a * b;
assert(a == 0 || c / a == b);
return c;
}
function div(uint256 a, uint256 b) internal returns (uint256) {
// assert(b > 0); // Solidity automatically throws when dividing by 0
uint256 c = a / b;
// assert(a == b * c + a % b); // There is no case in which this doesn't hold
return c;
}
function sub(uint256 a, uint256 b) internal returns (uint256) {
assert(b <= a);
return a - b;
}
function add(uint256 a, uint256 b) internal returns (uint256) {
uint256 c = a + b;
assert(c >= a);
return c;
}
}
contract ERC20Basic {
uint256 public totalSupply;
function balanceOf(address who) constant returns (uint256);
function transfer(address to, uint256 value) returns (bool);
event Transfer(address indexed from, address indexed to, uint256 value);
}
contract ERC20 is ERC20Basic {
function allowance(address owner, address spender) constant returns (uint256);
function transferFrom(address from, address to, uint256 value) returns (bool);
function approve(address spender, uint256 value) returns (bool);
event Approval(address indexed owner, address indexed spender, uint256 value);
}
contract BasicToken is ERC20Basic {
using SafeMath for uint256;
mapping(address => uint256) balances;
/**
* @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, uint256 _value) returns (bool) {
balances[msg.sender] = balances[msg.sender].sub(_value);
balances[_to] = balances[_to].add(_value);
Transfer(msg.sender, _to, _value);
return true;
}
/**
* @dev Gets the balance of the specified address.
* @param _owner The address to query the the balance of.
* @return An uint256 representing the amount owned by the passed address.
*/
function balanceOf(address _owner) constant returns (uint256 balance) {
return balances[_owner];
}
}
contract StandardToken is ERC20, BasicToken {
mapping (address => mapping (address => uint256)) 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 uint256 the amount of tokens to be transferred
*/
function transferFrom(address _from, address _to, uint256 _value) returns (bool) {
var _allowance = allowed[_from][msg.sender];
// Check is not needed because sub(_allowance, _value) will already throw if this condition is not met
// require (_value <= _allowance);
balances[_from] = balances[_from].sub(_value);
balances[_to] = balances[_to].add(_value);
allowed[_from][msg.sender] = _allowance.sub(_value);
Transfer(_from, _to, _value);
return true;
}
/**
* @dev Approve the passed address to spend the specified amount of tokens on behalf 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, uint256 _value) returns (bool) {
// 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
require((_value == 0) || (allowed[msg.sender][_spender] == 0));
allowed[msg.sender][_spender] = _value;
Approval(msg.sender, _spender, _value);
return true;
}
/**
* @dev Function to check the amount of tokens that 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 uint256 specifying the amount of tokens still available for the spender.
*/
function allowance(address _owner, address _spender) constant returns (uint256 remaining) {
return allowed[_owner][_spender];
}
}
contract Ownable {
address public owner;
/**
* @dev The Ownable constructor sets the original `owner` of the contract to the sender
* account.
*/
function Ownable() {
owner = msg.sender;
}
/**
* @dev Throws if called by any account other than the owner.
*/
modifier onlyOwner() {
require(msg.sender == owner);
_;
}
/**
* @dev Allows the current owner to transfer control of the contract to a newOwner.
* @param newOwner The address to transfer ownership to.
*/
function transferOwnership(address newOwner) onlyOwner {
require(newOwner != address(0));
owner = newOwner;
}
}
contract MintableToken is StandardToken, Ownable {
event Mint(address indexed to, uint256 amount);
event MintFinished();
bool public mintingFinished = false;
string public name = "Sample Ethereum Token";
string public symbol = "SET";
uint256 public decimals = 18;
modifier canMint() {
require(!mintingFinished);
_;
}
/**
* @dev Function to mint tokens
* @param _to The address that will receive the minted tokens.
* @param _amount The amount of tokens to mint.
* @return A boolean that indicates if the operation was successful.
*/
function mint(address _to, uint256 _amount) onlyOwner canMint returns (bool) {
totalSupply = totalSupply.add(_amount);
balances[_to] = balances[_to].add(_amount);
Mint(_to, _amount);
Transfer(0x0, _to, _amount);
return true;
}
/**
* @dev Function to stop minting new tokens.
* @return True if the operation was successful.
*/
function finishMinting() onlyOwner returns (bool) {
mintingFinished = true;
MintFinished();
return true;
}
}
contract Crowdsale {
using SafeMath for uint256;
// The token being sold
MintableToken public token;
// start and end block where investments are allowed (both inclusive)
uint256 public startBlock;
uint256 public endBlock;
// address where funds are collected
address public wallet;
// how many token units a buyer gets per wei
uint256 public rate;
// amount of raised money in wei
uint256 public weiRaised;
/**
* event for token purchase logging
* @param purchaser who paid for the tokens
* @param beneficiary who got the tokens
* @param value weis paid for purchase
* @param amount amount of tokens purchased
*/
event TokenPurchase(address indexed purchaser, address indexed beneficiary, uint256 value, uint256 amount);
function Crowdsale(uint256 _startBlock, uint256 _endBlock, uint256 _rate, address _wallet) {
require(_endBlock >= _startBlock);
require(_rate > 0);
require(_wallet != 0x0);
token = createTokenContract();
startBlock = _startBlock;
endBlock = _endBlock;
rate = _rate;
wallet = _wallet;
}
// creates the token to be sold.
// override this method to have crowdsale of a specific mintable token.
function createTokenContract() internal returns (MintableToken) {
return new MintableToken();
}
// fallback function can be used to buy tokens
function () payable {
buyTokens(msg.sender);
}
// low level token purchase function
function buyTokens(address beneficiary) payable {
require(beneficiary != 0x0);
require(validPurchase());
uint256 weiAmount = msg.value;
uint256 updatedWeiRaised = weiRaised.add(weiAmount);
// calculate token amount to be created
uint256 tokens = weiAmount.mul(rate);
// update state
weiRaised = updatedWeiRaised;
token.mint(beneficiary, tokens);
TokenPurchase(msg.sender, beneficiary, weiAmount, tokens);
forwardFunds();
}
// send ether to the fund collection wallet
// override to create custom fund forwarding mechanisms
function forwardFunds() internal {
wallet.transfer(msg.value);
}
// @return true if the transaction can buy tokens
function validPurchase() internal constant returns (bool) {
uint256 current = block.number;
bool withinPeriod = current >= startBlock && current <= endBlock;
bool nonZeroPurchase = msg.value != 0;
return withinPeriod && nonZeroPurchase;
}
// @return true if crowdsale event has ended
function hasEnded() public constant returns (bool) {
return block.number > endBlock;
}
}
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