pragma solidity ^0.4.26;


// Math operations with safety checks that throw on error
library SafeMath {
    
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a);
        return c;
    }
  
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a);
        return a - b;
    }
  
}


// Abstract contract for the full ERC 20 Token standard
contract ERC20 {
    
    function balanceOf(address _address) public view returns (uint256 balance);
    
    function transfer(address _to, uint256 _value) public returns (bool success);
    
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success);
    
    function approve(address _spender, uint256 _value) public returns (bool success);
    
    function allowance(address _owner, address _spender) public view returns (uint256 remaining);

    event Transfer(address indexed _from, address indexed _to, uint256 _value);
    
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
    
}


// Token contract
contract BHDT is ERC20 {
    
    string public name = "Bounty Hunter DEX Token";
    string public symbol = "BHDT";
    uint8 public decimals = 18;
    // 总发行量1千个
    uint256 public totalSupply = 1000 * 10**18;
    mapping (address => uint256) public balances;
    mapping (address => mapping (address => uint256)) public allowed;
    
    constructor() public {
        balances[msg.sender] = totalSupply;
    }
    
    function balanceOf(address _address) public view returns (uint256 balance) {
        return balances[_address];
    }
    
    function transfer(address _to, uint256 _value) public returns (bool success) {
        require(_to != address(0));
        require(balances[msg.sender] >= _value && _value > 0, "Insufficient balance or zero amount");
        balances[msg.sender] = SafeMath.sub(balances[msg.sender], _value);
        balances[_to] = SafeMath.add(balances[_to], _value);
        emit Transfer(msg.sender, _to, _value);
        return true;
    }
    
    function approve(address _spender, uint256 _amount) public returns (bool success) {
        require(_spender != address(0));
        require((allowed[msg.sender][_spender] == 0) || (_amount == 0));
        allowed[msg.sender][_spender] = _amount;
        emit Approval(msg.sender, _spender, _amount);
        return true;
    }
    
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
        require(_from != address(0) && _to != address(0));
        require(balances[_from] >= _value && allowed[_from][msg.sender] >= _value && _value > 0, "Insufficient balance or zero amount");
        balances[_from] = SafeMath.sub(balances[_from], _value);
        balances[_to] = SafeMath.add(balances[_to], _value);
        allowed[_from][msg.sender] = SafeMath.sub(allowed[_from][msg.sender], _value);
        emit Transfer(_from, _to, _value);
        return true;
    }
    
    function allowance(address _owner, address _spender) public view returns (uint256 remaining) {
        return allowed[_owner][_spender];
    }
    
    
}