ERC-20
Overview
Max Total Supply
10,000,000,000 STASIA
Holders
1,276
Market
Onchain Market Cap
$0.00
Circulating Supply Market Cap
-
Other Info
Token Contract (WITH 18 Decimals)
Balance
2,800 STASIAValue
$0.00Loading...
Loading
Loading...
Loading
Loading...
Loading
# | Exchange | Pair | Price | 24H Volume | % Volume |
---|
Contract Name:
Stasia
Compiler Version
v0.4.24+commit.e67f0147
Optimization Enabled:
Yes with 200 runs
Other Settings:
default evmVersion
Contract Source Code (Solidity)
/** *Submitted for verification at Etherscan.io on 2019-01-15 */ pragma solidity ^0.4.24; interface IERC20 { function totalSupply() external view returns (uint256); function balanceOf(address who) external view returns (uint256); function allowance(address owner, address spender) external view returns (uint256); function transfer(address to, uint256 value) external returns (bool); function approve(address spender, uint256 value) external returns (bool); function transferFrom(address from, address to, uint256 value) external returns (bool); event Transfer(address indexed from, address indexed to, uint256 value); event Approval(address indexed owner, address indexed spender, uint256 value); } library SafeMath { int256 constant private INT256_MIN = -2**255; /** * @dev Multiplies two unsigned integers, reverts on overflow. */ function mul(uint256 a, uint256 b) internal pure returns (uint256) { // Gas optimization: this is cheaper than requiring 'a' not being zero, but the // benefit is lost if 'b' is also tested. // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522 if (a == 0) { return 0; } uint256 c = a * b; require(c / a == b); return c; } /** * @dev Multiplies two signed integers, reverts on overflow. */ function mul(int256 a, int256 b) internal pure returns (int256) { // Gas optimization: this is cheaper than requiring 'a' not being zero, but the // benefit is lost if 'b' is also tested. // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522 if (a == 0) { return 0; } require(!(a == -1 && b == INT256_MIN)); // This is the only case of overflow not detected by the check below int256 c = a * b; require(c / a == b); return c; } /** * @dev Integer division of two unsigned integers truncating the quotient, reverts on division by zero. */ function div(uint256 a, uint256 b) internal pure returns (uint256) { // Solidity only automatically asserts when dividing by 0 require(b > 0); uint256 c = a / b; // assert(a == b * c + a % b); // There is no case in which this doesn't hold return c; } /** * @dev Integer division of two signed integers truncating the quotient, reverts on division by zero. */ function div(int256 a, int256 b) internal pure returns (int256) { require(b != 0); // Solidity only automatically asserts when dividing by 0 require(!(b == -1 && a == INT256_MIN)); // This is the only case of overflow int256 c = a / b; return c; } /** * @dev Subtracts two unsigned integers, reverts on overflow (i.e. if subtrahend is greater than minuend). */ function sub(uint256 a, uint256 b) internal pure returns (uint256) { require(b <= a); uint256 c = a - b; return c; } /** * @dev Subtracts two signed integers, reverts on overflow. */ function sub(int256 a, int256 b) internal pure returns (int256) { int256 c = a - b; require((b >= 0 && c <= a) || (b < 0 && c > a)); return c; } /** * @dev Adds two unsigned integers, reverts on overflow. */ function add(uint256 a, uint256 b) internal pure returns (uint256) { uint256 c = a + b; require(c >= a); return c; } /** * @dev Adds two signed integers, reverts on overflow. */ function add(int256 a, int256 b) internal pure returns (int256) { int256 c = a + b; require((b >= 0 && c >= a) || (b < 0 && c < a)); return c; } /** * @dev Divides two unsigned integers and returns the remainder (unsigned integer modulo), * reverts when dividing by zero. */ function mod(uint256 a, uint256 b) internal pure returns (uint256) { require(b != 0); return a % b; } } contract ERC20 is IERC20 { using SafeMath for uint256; mapping (address => uint256) private _balances; mapping (address => mapping (address => uint256)) private _allowed; uint256 private _totalSupply; /** * @dev Total number of tokens in existence */ function totalSupply() public view returns (uint256) { return _totalSupply; } /** * @dev Gets the balance of the specified address. * @param owner The address to query the balance of. * @return An uint256 representing the amount owned by the passed address. */ function balanceOf(address owner) public view returns (uint256) { return _balances[owner]; } /** * @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) public view returns (uint256) { return _allowed[owner][spender]; } /** * @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) public returns (bool) { _transfer(msg.sender, to, value); return true; } /** * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender. * Beware that changing an allowance with this method brings the risk that someone may use both the old * and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this * race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards: * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729 * @param spender The address which will spend the funds. * @param value The amount of tokens to be spent. */ function approve(address spender, uint256 value) public returns (bool) { require(spender != address(0)); _allowed[msg.sender][spender] = value; emit Approval(msg.sender, spender, value); return true; } /** * @dev Transfer tokens from one address to another. * Note that while this function emits an Approval event, this is not required as per the specification, * and other compliant implementations may not emit the event. * @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) public returns (bool) { _allowed[from][msg.sender] = _allowed[from][msg.sender].sub(value); _transfer(from, to, value); emit Approval(from, msg.sender, _allowed[from][msg.sender]); return true; } /** * @dev Increase the amount of tokens that an owner allowed to a spender. * approve should be called when allowed_[_spender] == 0. To increment * allowed value is better to use this function to avoid 2 calls (and wait until * the first transaction is mined) * From MonolithDAO Token.sol * Emits an Approval event. * @param spender The address which will spend the funds. * @param addedValue The amount of tokens to increase the allowance by. */ function increaseAllowance(address spender, uint256 addedValue) public returns (bool) { require(spender != address(0)); _allowed[msg.sender][spender] = _allowed[msg.sender][spender].add(addedValue); emit Approval(msg.sender, spender, _allowed[msg.sender][spender]); return true; } /** * @dev Decrease the amount of tokens that an owner allowed to a spender. * approve should be called when allowed_[_spender] == 0. To decrement * allowed value is better to use this function to avoid 2 calls (and wait until * the first transaction is mined) * From MonolithDAO Token.sol * Emits an Approval event. * @param spender The address which will spend the funds. * @param subtractedValue The amount of tokens to decrease the allowance by. */ function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) { require(spender != address(0)); _allowed[msg.sender][spender] = _allowed[msg.sender][spender].sub(subtractedValue); emit Approval(msg.sender, spender, _allowed[msg.sender][spender]); return true; } /** * @dev Transfer token for a specified addresses * @param from The address to transfer from. * @param to The address to transfer to. * @param value The amount to be transferred. */ function _transfer(address from, address to, uint256 value) internal { require(to != address(0)); _balances[from] = _balances[from].sub(value); _balances[to] = _balances[to].add(value); emit Transfer(from, to, value); } /** * @dev Internal function that mints an amount of the token and assigns it to * an account. This encapsulates the modification of balances such that the * proper events are emitted. * @param account The account that will receive the created tokens. * @param value The amount that will be created. */ function _mint(address account, uint256 value) internal { require(account != address(0)); _totalSupply = _totalSupply.add(value); _balances[account] = _balances[account].add(value); emit Transfer(address(0), account, value); } /** * @dev Internal function that burns an amount of the token of a given * account. * @param account The account whose tokens will be burnt. * @param value The amount that will be burnt. */ function _burn(address account, uint256 value) internal { require(account != address(0)); _totalSupply = _totalSupply.sub(value); _balances[account] = _balances[account].sub(value); emit Transfer(account, address(0), value); } /** * @dev Internal function that burns an amount of the token of a given * account, deducting from the sender's allowance for said account. Uses the * internal burn function. * Emits an Approval event (reflecting the reduced allowance). * @param account The account whose tokens will be burnt. * @param value The amount that will be burnt. */ function _burnFrom(address account, uint256 value) internal { _allowed[account][msg.sender] = _allowed[account][msg.sender].sub(value); _burn(account, value); emit Approval(account, msg.sender, _allowed[account][msg.sender]); } } contract ERC20Detailed is IERC20 { string private _name; string private _symbol; uint8 private _decimals; constructor (string name, string symbol, uint8 decimals) public { _name = name; _symbol = symbol; _decimals = decimals; } /** * @return the name of the token. */ function name() public view returns (string) { return _name; } /** * @return the symbol of the token. */ function symbol() public view returns (string) { return _symbol; } /** * @return the number of decimals of the token. */ function decimals() public view returns (uint8) { return _decimals; } } contract ERC20Burnable is ERC20 { /** * @dev Burns a specific amount of tokens. * @param value The amount of token to be burned. */ function burn(uint256 value) public { _burn(msg.sender, value); } /** * @dev Burns a specific amount of tokens from the target address and decrements allowance * @param from address The address which you want to send tokens from * @param value uint256 The amount of token to be burned */ function burnFrom(address from, uint256 value) public { _burnFrom(from, value); } } contract Stasia is ERC20, ERC20Detailed, ERC20Burnable { uint256 public constant INITIAL_SUPPLY = 10000000000 * 10**18; /** * @dev Constructor that gives msg.sender all of existing tokens. */ constructor () public ERC20Detailed("STASIA", "STASIA", 18) { _mint(msg.sender, INITIAL_SUPPLY); } }
Contract Security Audit
- No Contract Security Audit Submitted- Submit Audit Here
[{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"spender","type":"address"},{"name":"value","type":"uint256"}],"name":"approve","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"from","type":"address"},{"name":"to","type":"address"},{"name":"value","type":"uint256"}],"name":"transferFrom","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"INITIAL_SUPPLY","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint8"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"spender","type":"address"},{"name":"addedValue","type":"uint256"}],"name":"increaseAllowance","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"value","type":"uint256"}],"name":"burn","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"owner","type":"address"}],"name":"balanceOf","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"from","type":"address"},{"name":"value","type":"uint256"}],"name":"burnFrom","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"spender","type":"address"},{"name":"subtractedValue","type":"uint256"}],"name":"decreaseAllowance","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"to","type":"address"},{"name":"value","type":"uint256"}],"name":"transfer","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"owner","type":"address"},{"name":"spender","type":"address"}],"name":"allowance","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"inputs":[],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"anonymous":false,"inputs":[{"indexed":true,"name":"from","type":"address"},{"indexed":true,"name":"to","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Transfer","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"owner","type":"address"},{"indexed":true,"name":"spender","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Approval","type":"event"}]
Contract Creation Code
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
Deployed Bytecode
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
Swarm Source
bzzr://26317decee10f58af9d471ff4cd5891703ffd290c53e3327f3870e68db413e07
Loading...
Loading
Loading...
Loading
[ Download: CSV Export ]
[ Download: CSV Export ]
A token is a representation of an on-chain or off-chain asset. The token page shows information such as price, total supply, holders, transfers and social links. Learn more about this page in our Knowledge Base.