Contract Source Code:
File 1 of 1 : GRIC_COIN
/**
*Submitted for verification at Etherscan.io on 2019-10-10
*/
/**
*Submitted for verification at Etherscan.io on 2019-08-29
*/
pragma solidity ^0.5.11;
contract ERC20 {
function balanceOf(address who) public view returns (uint256);
function allowance(address owner, address spender) public view returns (uint256);
function transferFrom(address from, address to, uint256 value) public returns (bool);
function approve(address spender, uint256 value) public returns (bool);
function transfer(address to, uint value) public returns(bool);
event Transfer(address indexed from, address indexed to, uint value);
event Approval(address indexed owner, address indexed spender, uint256 value);
}
library SafeMath{
function mul(uint256 a, uint256 b) internal pure returns (uint256)
{
if (a == 0) {
return 0;}
uint256 c = a * b;
assert(c / a == b);
return c;
}
function div(uint256 a, uint256 b) internal pure returns (uint256)
{
uint256 c = a / b;
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 GRIC_COIN is ERC20 {
using SafeMath for uint256;
string internal _name;
string internal _symbol;
uint8 internal _decimals;
uint256 internal _totalSupply;
address internal _admin;
uint256 public exchangeRate; //percentage
address public tokenaddress;
mapping (address => uint256) internal balances;
mapping (address => mapping (address => uint256)) internal allowed;
event oldtokenhistory(address tokenaddress,address _from, address _to,uint256 _amount);
constructor(uint256 _rate,address _tokenaddress) public {
_admin = msg.sender;
_symbol = "GC";
_name = "Gric Coin";
_decimals = 18;
_totalSupply = 20000000* 10**uint(_decimals);
balances[msg.sender]=_totalSupply;
exchangeRate = _rate;
tokenaddress = _tokenaddress;
}
modifier ownership() {
require(msg.sender == _admin);
_;
}
function name() public view returns (string memory)
{
return _name;
}
function symbol() public view returns (string memory)
{
return _symbol;
}
function decimals() public view returns (uint8)
{
return _decimals;
}
function totalSupply() public view returns (uint256)
{
return _totalSupply;
}
function transfer(address _to, uint256 _value) public returns (bool) {
require(_to != address(0));
require(_value <= balances[msg.sender]);
balances[msg.sender] = balances[msg.sender].sub(_value);
balances[_to] = (balances[_to]).add( _value);
emit ERC20.Transfer(msg.sender, _to, _value);
return true;
}
function balanceOf(address _owner) public view returns (uint256 balance) {
return balances[_owner];
}
function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
require(_to != address(0));
require(_value <= balances[_from]);
require(_value <= allowed[_from][msg.sender]);
balances[_from] = (balances[_from]).sub( _value);
balances[_to] = (balances[_to]).add(_value);
allowed[_from][msg.sender] = (allowed[_from][msg.sender]).sub(_value);
emit ERC20.Transfer(_from, _to, _value);
return true;
}
function approve(address _spender, uint256 _value) public returns (bool) {
allowed[msg.sender][_spender] = _value;
emit ERC20.Approval(msg.sender, _spender, _value);
return true;
}
function allowance(address _owner, address _spender) public view returns (uint256) {
return allowed[_owner][_spender];
}
function mint(uint256 _amount) public ownership returns (bool) {
_totalSupply = (_totalSupply).add(_amount);
balances[_admin] +=_amount;
return true;
}
function exchange(uint256 _amount) public{ //amountA = value //_rate= ratio value
uint256 total = (_amount.div(1000)).mul(exchangeRate) ;
require(balances[_admin]>=total);
ERC20(tokenaddress).transferFrom(msg.sender,address(this), _amount); //after allowance
balances[_admin]= (balances[_admin]).sub(total);
balances[msg.sender] = (balances[msg.sender]).add(total);
emit ERC20.Transfer(_admin,msg.sender,total);
emit oldtokenhistory(tokenaddress,msg.sender,address(this),_amount);
}
// owner can update the ratio rate of old token
function updateRate(uint256 _rate) public returns(bool) {
require(msg.sender==_admin);
exchangeRate = _rate;
return true;
}
//owner can update the old token address
function updatetokenaddress(address _tokenaddress) public returns(bool) {
require(msg.sender==_admin);
tokenaddress = _tokenaddress;
return true;
}
//only admin can initiate this function
//he can transfer the old token to him or any body else
function withdrawoldtoken(uint256 amount, address to) public returns (bool){
require(msg.sender==_admin && uint256(ERC20(tokenaddress).balanceOf(address(this)))>=amount);
ERC20(tokenaddress).transferFrom(address(this),to,amount);
emit oldtokenhistory(tokenaddress,address(this),to,amount);
return true;
}
//Admin can transfer his ownership to new address
function transferownership(address _newaddress) public returns(bool){
require(msg.sender==_admin);
_admin=_newaddress;
return true;
}
}