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@ImanMousavi
Created October 30, 2020 09:59
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pragma solidity ^0.6.0;
interface IERC20 {
function totalSupply() external view returns (uint256);
function balanceOf(address account) external view returns (uint256);
function allowance(address owner, address spender) external view returns (uint256);
function transfer(address recipient, uint256 amount) external returns (bool);
function approve(address spender, uint256 amount) external returns (bool);
function transferFrom(address sender, address recipient, uint256 amount) 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 {
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 DEX {
event Bought(uint256 amount);
event Sold(uint256 amount);
IERC20 public token;
constructor(address _token) public {
token = IERC20(_token);
}
function buy() payable public {
uint256 amountTobuy = msg.value;
uint256 dexBalance = token.balanceOf(address(this));
require(amountTobuy > 0, "You need to send some Ether");
require(amountTobuy <= dexBalance, "Not enough tokens in the reserve");
token.transfer(msg.sender, amountTobuy);
emit Bought(amountTobuy);
}
function sell(uint256 amount) public {
require(amount > 0, "You need to sell at least some tokens");
uint256 allowance = token.allowance(msg.sender, address(this));
require(allowance >= amount, "Check the token allowance");
token.transferFrom(msg.sender, address(this), amount);
msg.sender.transfer(amount);
emit Sold(amount);
}
}
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