I am compiling the ERC20Basic contract on the Remix, so I receive the token code and I can send BNB for this contract.

However, when I send BNB the function to send me the contract tokens that I created in ERC20Basic is in the DEX contract.

I do not understand how it is possible to do this sending since I compile only the ERC20Basic in Remix, and not DEX.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

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);


contract ERC20Basic is IERC20{

    string public constant name = "ByeSeel";
    string public constant symbol = "BYS";
    uint8 public constant decimals = 18;

//event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
//event Transfer(address indexed from, address indexed to, uint tokens);

mapping(address => uint256) balances;

mapping(address => mapping (address => uint256)) allowed;

uint256 totalSupply_ = 10000000 * 10 ** 18;

using SafeMath for uint256;

constructor() {
    balances[msg.sender] = totalSupply_;

function totalSupply() public override view returns (uint256) {
    return totalSupply_;

function balanceOf(address tokenOwner) public override view returns (uint256) {
    return balances[tokenOwner];

function transfer(address receiver, uint256 numTokens) public override returns (bool) {
    require(numTokens <= balances[msg.sender]);
    balances[msg.sender] = balances[msg.sender].sub(numTokens);
    balances[receiver] = balances[receiver].add(numTokens);
    emit Transfer(msg.sender, receiver, numTokens);
    return true;

function approve(address delegate, uint256 numTokens) public override returns (bool) {
    allowed[msg.sender][delegate] = numTokens;
    emit Approval(msg.sender, delegate, numTokens);
    return true;

function allowance(address owner, address delegate) public override view returns (uint) {
return allowed[owner][delegate];

function transferFrom(address owner, address buyer, uint256 numTokens) public override returns (bool) {
require(numTokens <= balances[owner]);
require(numTokens <= allowed[owner][msg.sender]);

balances[owner] = balances[owner].sub(numTokens);
allowed[owner][msg.sender] = allowed[owner][msg.sender].sub(numTokens);
balances[buyer] = balances[buyer].add(numTokens);
emit Transfer(owner, buyer, numTokens);
return true;

event Received(address, uint);
 receive() external payable {
 emit Received(msg.sender, msg.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() {
        token = new ERC20Basic();

    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);
        emit Sold(amount);

    receive() external payable {


In this case, I just want to send BNB and return my token, but I don't know if I will compile the ERC20Basic contract or the DEX contract.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.