gistfile1.txt

// latest version https://github.com/ethereum/solidity/releases 0.4.24
pragma solidity ^0.4.24;

contract ERC20 {
  //string public constant name = "Token Name";
  //string public constant symbol = "SYM";
  //uint8 public constant decimals = 18;
  
  function totalSupply() public constant returns (uint256);
  function balanceOf(address _owner) public constant returns (uint256);
  function transfer(address _to, uint256 _value) public returns (bool);

  function transferFrom(address _from, address _to, uint256 _value) public  returns (bool);
  function approve(address _spender, uint256 _value) public returns (bool);
  function allowance(address _owner, address _spender) public constant returns (uint256);

  event Approval(address indexed _owner, address indexed _spender, uint256 _value);

  event Transfer(address indexed _from, address indexed _to, uint256 _value);

}

library SafeMath {
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a * b;
    assert(a == 0 || c / a == b);
    return c;
  }

  function div(uint256 a, uint256 b) internal pure 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 pure returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    assert(c >= a);
    return c;
  }
}

contract Owned {
    address public owner;
    address public newOwner;

    event OwnershipTransferred(address indexed _from, address indexed _to);

    constructor() public {
        owner = msg.sender;
    }

    modifier onlyOwner {
        require(msg.sender == owner);
        _;
    }

    function transferOwnership(address _newOwner) public onlyOwner {
        newOwner = _newOwner;
    }
    function acceptOwnership() public {
        require(msg.sender == newOwner);
        emit OwnershipTransferred(owner, newOwner);
        owner = newOwner;
        newOwner = address(0);
    }
}

contract ExampleToken is ERC20, Owned {
  using SafeMath for uint256;
  
  string public name;
  string public symbol;
  uint8 public decimals;
  
  uint256 supply;
  mapping (address => uint256) balances;
  mapping (address => mapping(address => uint256)) allowances;
  
   constructor() public {
    symbol = "EXAMPLE";
    name = "Example token";
    decimals = 18;
    supply = 21000000 * 10**uint(decimals);
    balances[owner] = supply;
    emit Transfer(address(0), owner, supply);
  }
  
  
  function totalSupply() constant public returns (uint256) {
    return supply;
  }

  function allowance(address _owner, address _spender) public constant
returns (uint256 remaining) {
    return allowances[_owner][_spender];
  }

  function balanceOf(address _owner) constant returns (uint256 balance) {
    return balances[_owner];
  }

  function transfer(address _to, uint256 _value) public returns (bool success) {
    require(_value <= balances[msg.sender]);
    //require(_to != address(0));

    // SafeMath.sub will throw if there is not enough balance.
    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);
    emit Transfer(msg.sender, _to, _value);
    return true;
  }

  function approve(address _spender, uint256 _value) returns (bool success) {
    allowances[msg.sender][_spender] = _value;
    emit Approval(msg.sender, _spender, _value);
    return true;
  }

  function transferFrom(address _from, address _to, uint256 _value)
returns (bool success) {
    require(_to != address(0));
    require(_value <= balances[_from]);
    require(_value <= allowances[_from][msg.sender]);

    balances[_from] = balances[_from].sub(_value);
    balances[_to] = balances[_to].add(_value);
    allowances[_from][msg.sender] = allowances[_from][msg.sender].sub(_value);
    emit Transfer(_from, _to, _value);
  }
  
  
}