Solidity – ERC20 Token Initialization with Uniswap V2 Router Address and Method to Alter Address

remixsolidityuniswapuniswapv2

I'm working on ERC20 token with a uniswapV2 router address initialized in the constructor. I also have method to change the router address. but I'm confused because when i create the new Pair with a different router address. The router Address variable updates.
My question is even after the updated router address for example from uniswap to sushiswap. can a user will still be able to buy/sell on uniswap?

IUniswapV2Router02 public UniswapV2Router ;
    address[] public UniswapV2Pairs;

constructor() ERC20("Hello", "HEY") {
UniswapV2Router = IUniswapV2Router02(0xC532a74256D3Db42D0Bf7a0400fEFDbad7694008);
address _UniswapV2Pair = IUniswapV2Factory(UniswapV2Router.factory()).createPair(address(this), UniswapV2Router.WETH());
UniswapV2Pairs.push(_UniswapV2Pair)
}

function addPairAddress(address newPair) external onlyOwner {
    require(newPair != address(0), "Invalid pair address");
    UniswapV2Pairs.push(newPair);
   
}

 function changeRouterAddress(address newRouter) external onlyOwner {
    require(newRouter != address(0), "Invalid router address");
        UniswapV2Router = IUniswapV2Router02(newRouter);
    address _UniswapV2Pair = IUniswapV2Factory(UniswapV2Router.factory())
        .createPair(address(this), UniswapV2Router.WETH());
    UniswapV2Pairs.push(_UniswapV2Pair);
}


function swapTokensForEth(uint256 tokenAmount) private {
        address[] memory path = new address[](2);
        path[0] = address(this);
        path[1] = UniswapV2Router.WETH();
        _approve(address(this), address(UniswapV2Router), tokenAmount);
        UniswapV2Router.swapExactTokensForETHSupportingFeeOnTransferTokens(
            tokenAmount,
            0,
            path,
            address(this),
            block.timestamp + 200
        );
    }

this is the code. my original router is uniswapv2 after adding a new router( sushiswap) the variable UniswapV2Router is updated with sushiswap address.
Can i still be able to buy/sell on uniswap?

Best Answer

addPairAddress() just pushes the address into UniswapV2Pairs[], it doesn't update the router address.

changeRouterAddress() updates the router address and creates a new pair by calling the factory listed at the router address. Pair is for the wrapped native coin listed at the router, and your calling token contract.

Swap just calls swapExactTokensForETHSupportingFeeOnTransferTokens() on the stored router, if you update the router address the function will swap on that new pool from that new factory. The old pool will still exist and people will be able to swap on it but not by calling your function, that will only swap on the one pool from the factory listed at the router.

On a side note you might want to test if swaps get sandwiched, as you are using 0 for the minimum output amount. Unless you are going to have it called as part of an atomic operation that does make a safety check.

Related Solutions

Solidity – Purpose of Declaring Router Address in a Solidity Constructor

You absolutely can initialize it later, most of the programmers do it in this way because is a good practice to initialize your resources at the constructor, but it might not be your case. You can initialize whenever is reasonable based in your business logic

ERC-20 Deployment on Testnet – Fixing Deployment Issues with Uniswap Router

The error refers is storage out of gas. For bypass this error use can use the import of libraries.

Try this:

// SPDX-License-Identifier: Unlicensed 
pragma solidity ^0.8.4;
 
import "@openzeppelin/contracts/utils/Context.sol";
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@uniswap/v2-core/contracts/interfaces/IUniswapV2Factory.sol";
import "@uniswap/v2-core/contracts/interfaces/IUniswapV2Pair.sol";
import "@uniswap/v2-periphery/contracts/interfaces/IUniswapV2Router01.sol";
import "@uniswap/v2-periphery/contracts/interfaces/IUniswapV2Router02.sol";


library Address {
 
    function isContract(address account) internal view returns (bool) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != accountHash && codehash != 0x0);
    }
 
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");
 
        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }
 
 
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }
 
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return _functionCallWithValue(target, data, 0, errorMessage);
    }
 
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }
 
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        return _functionCallWithValue(target, data, value, errorMessage);
    }
 
    function _functionCallWithValue(address target, bytes memory data, uint256 weiValue, string memory errorMessage) private returns (bytes memory) {
        require(isContract(target), "Address: call to non-contract");
 
        (bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
        if (success) {
            return returndata;
        } else {
 
            if (returndata.length > 0) {
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}
 

contract CronosNaut is Context, IERC20, Ownable {
    using SafeMath for uint256;
    using Address for address;
 
    address payable public marketingAddress = payable(0x3bfC545BdE045e3eef6Ce2e75928946D7C5591f8); // Marketing Address
    address public immutable deadAddress = 0x000000000000000000000000000000000000dEaD;
    mapping (address => uint256) private _rOwned;
    mapping (address => uint256) private _tOwned;
    mapping (address => mapping (address => uint256)) private _allowances;
 
    mapping (address => bool) private _isExcludedFromFee;
 
    mapping (address => bool) private _isExcluded;
    address[] private _excluded;
 
    uint256 private constant MAX = ~uint256(0);
    uint256 private _tTotal = 1000000000 * 10**6 * 10**9;
    uint256 private _rTotal = (MAX - (MAX % _tTotal));
    uint256 private _tFeeTotal;
 
    string private _name = "CronosNaut";
    string private _symbol = "CRON";
    uint8 private _decimals = 9;
 
 
    uint256 public _taxFee = 2;
    uint256 private _previousTaxFee = _taxFee;
 
    uint256 public _liquidityFee = 2;
    uint256 private _previousLiquidityFee = _liquidityFee;
 
    uint256 public marketingDivisor = 2;
 
    uint256 public _maxTxAmount = 3000000 * 10**6 * 10**9;
    uint256 private minimumTokensBeforeSwap = 200000 * 10**6 * 10**9; 
    uint256 private buyBackUpperLimit = 1 * 10**18;
 
    IUniswapV2Router02 public immutable uniswapV2Router;
    address public immutable uniswapV2Pair;
 
    bool inSwapAndLiquify;
    bool public swapAndLiquifyEnabled = false;
    bool public buyBackEnabled = true;
 
 
    event RewardLiquidityProviders(uint256 tokenAmount);
    event BuyBackEnabledUpdated(bool enabled);
    event SwapAndLiquifyEnabledUpdated(bool enabled);
    event SwapAndLiquify(
        uint256 tokensSwapped,
        uint256 ethReceived,
        uint256 tokensIntoLiqudity
    );
 
    event SwapETHForTokens(
        uint256 amountIn,
        address[] path
    );
 
    event SwapTokensForETH(
        uint256 amountIn,
        address[] path
    );
 
    modifier lockTheSwap {
        inSwapAndLiquify = true;
        _;
        inSwapAndLiquify = false;
    }
 
    constructor () {
        _rOwned[_msgSender()] = _rTotal;
        IUniswapV2Router02 _uniswapV2Router = IUniswapV2Router02(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
        uniswapV2Pair = IUniswapV2Factory(_uniswapV2Router.factory())
            .createPair(address(this), _uniswapV2Router.WETH());
 
        uniswapV2Router = _uniswapV2Router;
        _isExcludedFromFee[owner()] = true;
        _isExcludedFromFee[address(this)] = true;
 
        emit Transfer(address(0), _msgSender(), _tTotal);
    }
 
    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 override returns (uint256) {
        return _tTotal;
    }
 
    function balanceOf(address account) public view override returns (uint256) {
        if (_isExcluded[account]) return _tOwned[account];
        return tokenFromReflection(_rOwned[account]);
    }
 
    function transfer(address recipient, uint256 amount) public override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }
 
    function allowance(address owner, address spender) public view override returns (uint256) {
        return _allowances[owner][spender];
    }
 
    function approve(address spender, uint256 amount) public override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }
 
    function transferFrom(address sender, address recipient, uint256 amount) public override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }
 
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }
 
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }
 
    function isExcludedFromReward(address account) public view returns (bool) {
        return _isExcluded[account];
    }
 
    function totalFees() public view returns (uint256) {
        return _tFeeTotal;
    }
 
    function minimumTokensBeforeSwapAmount() public view returns (uint256) {
        return minimumTokensBeforeSwap;
    }
 
    function buyBackUpperLimitAmount() public view returns (uint256) {
        return buyBackUpperLimit;
    }
 
    function deliver(uint256 tAmount) public {
        address sender = _msgSender();
        require(!_isExcluded[sender], "Excluded addresses cannot call this function");
        (uint256 rAmount,,,,,) = _getValues(tAmount);
        _rOwned[sender] = _rOwned[sender].sub(rAmount);
        _rTotal = _rTotal.sub(rAmount);
        _tFeeTotal = _tFeeTotal.add(tAmount);
    }
 
 
    function reflectionFromToken(uint256 tAmount, bool deductTransferFee) public view returns(uint256) {
        require(tAmount <= _tTotal, "Amount must be less than supply");
        if (!deductTransferFee) {
            (uint256 rAmount,,,,,) = _getValues(tAmount);
            return rAmount;
        } else {
            (,uint256 rTransferAmount,,,,) = _getValues(tAmount);
            return rTransferAmount;
        }
    }
 
    function tokenFromReflection(uint256 rAmount) public view returns(uint256) {
        require(rAmount <= _rTotal, "Amount must be less than total reflections");
        uint256 currentRate =  _getRate();
        return rAmount.div(currentRate);
    }
 
    function excludeFromReward(address account) public onlyOwner() {
 
        require(!_isExcluded[account], "Account is already excluded");
        if(_rOwned[account] > 0) {
            _tOwned[account] = tokenFromReflection(_rOwned[account]);
        }
        _isExcluded[account] = true;
        _excluded.push(account);
    }
 
    function includeInReward(address account) external onlyOwner() {
        require(_isExcluded[account], "Account is already excluded");
        for (uint256 i = 0; i < _excluded.length; i++) {
            if (_excluded[i] == account) {
                _excluded[i] = _excluded[_excluded.length - 1];
                _tOwned[account] = 0;
                _isExcluded[account] = false;
                _excluded.pop();
                break;
            }
        }
    }
 
    function _approve(address owner, address spender, uint256 amount) private {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");
 
        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }
 
    function _transfer(
        address from,
        address to,
        uint256 amount
    ) private {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");
        require(amount > 0, "Transfer amount must be greater than zero");
        if(from != owner() && to != owner()) {
            require(amount <= _maxTxAmount, "Transfer amount exceeds the maxTxAmount.");
        }
 
        uint256 contractTokenBalance = balanceOf(address(this));
        bool overMinimumTokenBalance = contractTokenBalance >= minimumTokensBeforeSwap;
 
        if (!inSwapAndLiquify && swapAndLiquifyEnabled && to == uniswapV2Pair) {
            if (overMinimumTokenBalance) {
                contractTokenBalance = minimumTokensBeforeSwap;
                swapTokens(contractTokenBalance);    
            }
            uint256 balance = address(this).balance;
            if (buyBackEnabled && balance > uint256(1 * 10**18)) {
 
                if (balance > buyBackUpperLimit)
                    balance = buyBackUpperLimit;
 
                buyBackTokens(balance.div(100));
            }
        }
 
        bool takeFee = true;
 
        //if any account belongs to _isExcludedFromFee account then remove the fee
        if(_isExcludedFromFee[from] || _isExcludedFromFee[to]){
            takeFee = false;
        }
 
        _tokenTransfer(from,to,amount,takeFee);
    }
 
    function swapTokens(uint256 contractTokenBalance) private lockTheSwap {
 
        uint256 initialBalance = address(this).balance;
        swapTokensForEth(contractTokenBalance);
        uint256 transferredBalance = address(this).balance.sub(initialBalance);
 
        //Send to Marketing address
        transferToAddressETH(marketingAddress, transferredBalance.div(_liquidityFee).mul(marketingDivisor));
 
    }
 
 
    function buyBackTokens(uint256 amount) private lockTheSwap {
        if (amount > 0) {
            swapETHForTokens(amount);
        }
    }
 
    function swapTokensForEth(uint256 tokenAmount) private {
        // generate the uniswap pair path of token -> weth
        address[] memory path = new address[](2);
        path[0] = address(this);
        path[1] = uniswapV2Router.WETH();
 
        _approve(address(this), address(uniswapV2Router), tokenAmount);
 
        // make the swap
        uniswapV2Router.swapExactTokensForETHSupportingFeeOnTransferTokens(
            tokenAmount,
            0, // accept any amount of ETH
            path,
            address(this), // The contract
            block.timestamp
        );
 
        emit SwapTokensForETH(tokenAmount, path);
    }
 
    function swapETHForTokens(uint256 amount) private {
        // generate the uniswap pair path of token -> weth
        address[] memory path = new address[](2);
        path[0] = uniswapV2Router.WETH();
        path[1] = address(this);
 
      // make the swap
        uniswapV2Router.swapExactETHForTokensSupportingFeeOnTransferTokens{value: amount}(
            0, // accept any amount of Tokens
            path,
            deadAddress, // Burn address
            block.timestamp.add(300)
        );
 
        emit SwapETHForTokens(amount, path);
    }
 
    function addLiquidity(uint256 tokenAmount, uint256 ethAmount) private {
        // approve token transfer to cover all possible scenarios
        _approve(address(this), address(uniswapV2Router), tokenAmount);
 
        // add the liquidity
        uniswapV2Router.addLiquidityETH{value: ethAmount}(
            address(this),
            tokenAmount,
            0, // slippage is unavoidable
            0, // slippage is unavoidable
            owner(),
            block.timestamp
        );
    }
 
    function _tokenTransfer(address sender, address recipient, uint256 amount,bool takeFee) private {
        if(!takeFee)
            removeAllFee();
 
        if (_isExcluded[sender] && !_isExcluded[recipient]) {
            _transferFromExcluded(sender, recipient, amount);
        } else if (!_isExcluded[sender] && _isExcluded[recipient]) {
            _transferToExcluded(sender, recipient, amount);
        } else if (_isExcluded[sender] && _isExcluded[recipient]) {
            _transferBothExcluded(sender, recipient, amount);
        } else {
            _transferStandard(sender, recipient, amount);
        }
 
        if(!takeFee)
            restoreAllFee();
    }
 
    function _transferStandard(address sender, address recipient, uint256 tAmount) private {
        (uint256 rAmount, uint256 rTransferAmount, uint256 rFee, uint256 tTransferAmount, uint256 tFee, uint256 tLiquidity) = _getValues(tAmount);
        _rOwned[sender] = _rOwned[sender].sub(rAmount);
        _rOwned[recipient] = _rOwned[recipient].add(rTransferAmount);
        _takeLiquidity(tLiquidity);
        _reflectFee(rFee, tFee);
        emit Transfer(sender, recipient, tTransferAmount);
    }
 
    function _transferToExcluded(address sender, address recipient, uint256 tAmount) private {
        (uint256 rAmount, uint256 rTransferAmount, uint256 rFee, uint256 tTransferAmount, uint256 tFee, uint256 tLiquidity) = _getValues(tAmount);
        _rOwned[sender] = _rOwned[sender].sub(rAmount);
        _tOwned[recipient] = _tOwned[recipient].add(tTransferAmount);
        _rOwned[recipient] = _rOwned[recipient].add(rTransferAmount);           
        _takeLiquidity(tLiquidity);
        _reflectFee(rFee, tFee);
        emit Transfer(sender, recipient, tTransferAmount);
    }
 
    function _transferFromExcluded(address sender, address recipient, uint256 tAmount) private {
        (uint256 rAmount, uint256 rTransferAmount, uint256 rFee, uint256 tTransferAmount, uint256 tFee, uint256 tLiquidity) = _getValues(tAmount);
        _tOwned[sender] = _tOwned[sender].sub(tAmount);
        _rOwned[sender] = _rOwned[sender].sub(rAmount);
        _rOwned[recipient] = _rOwned[recipient].add(rTransferAmount);   
        _takeLiquidity(tLiquidity);
        _reflectFee(rFee, tFee);
        emit Transfer(sender, recipient, tTransferAmount);
    }
 
    function _transferBothExcluded(address sender, address recipient, uint256 tAmount) private {
        (uint256 rAmount, uint256 rTransferAmount, uint256 rFee, uint256 tTransferAmount, uint256 tFee, uint256 tLiquidity) = _getValues(tAmount);
        _tOwned[sender] = _tOwned[sender].sub(tAmount);
        _rOwned[sender] = _rOwned[sender].sub(rAmount);
        _tOwned[recipient] = _tOwned[recipient].add(tTransferAmount);
        _rOwned[recipient] = _rOwned[recipient].add(rTransferAmount);        
        _takeLiquidity(tLiquidity);
        _reflectFee(rFee, tFee);
        emit Transfer(sender, recipient, tTransferAmount);
    }
 
    function _reflectFee(uint256 rFee, uint256 tFee) private {
        _rTotal = _rTotal.sub(rFee);
        _tFeeTotal = _tFeeTotal.add(tFee);
    }
 
    function _getValues(uint256 tAmount) private view returns (uint256, uint256, uint256, uint256, uint256, uint256) {
        (uint256 tTransferAmount, uint256 tFee, uint256 tLiquidity) = _getTValues(tAmount);
        (uint256 rAmount, uint256 rTransferAmount, uint256 rFee) = _getRValues(tAmount, tFee, tLiquidity, _getRate());
        return (rAmount, rTransferAmount, rFee, tTransferAmount, tFee, tLiquidity);
    }
 
    function _getTValues(uint256 tAmount) private view returns (uint256, uint256, uint256) {
        uint256 tFee = calculateTaxFee(tAmount);
        uint256 tLiquidity = calculateLiquidityFee(tAmount);
        uint256 tTransferAmount = tAmount.sub(tFee).sub(tLiquidity);
        return (tTransferAmount, tFee, tLiquidity);
    }
 
    function _getRValues(uint256 tAmount, uint256 tFee, uint256 tLiquidity, uint256 currentRate) private pure returns (uint256, uint256, uint256) {
        uint256 rAmount = tAmount.mul(currentRate);
        uint256 rFee = tFee.mul(currentRate);
        uint256 rLiquidity = tLiquidity.mul(currentRate);
        uint256 rTransferAmount = rAmount.sub(rFee).sub(rLiquidity);
        return (rAmount, rTransferAmount, rFee);
    }
 
    function _getRate() private view returns(uint256) {
        (uint256 rSupply, uint256 tSupply) = _getCurrentSupply();
        return rSupply.div(tSupply);
    }
 
    function _getCurrentSupply() private view returns(uint256, uint256) {
        uint256 rSupply = _rTotal;
        uint256 tSupply = _tTotal;      
        for (uint256 i = 0; i < _excluded.length; i++) {
            if (_rOwned[_excluded[i]] > rSupply || _tOwned[_excluded[i]] > tSupply) return (_rTotal, _tTotal);
            rSupply = rSupply.sub(_rOwned[_excluded[i]]);
            tSupply = tSupply.sub(_tOwned[_excluded[i]]);
        }
        if (rSupply < _rTotal.div(_tTotal)) return (_rTotal, _tTotal);
        return (rSupply, tSupply);
    }
 
    function _takeLiquidity(uint256 tLiquidity) private {
        uint256 currentRate =  _getRate();
        uint256 rLiquidity = tLiquidity.mul(currentRate);
        _rOwned[address(this)] = _rOwned[address(this)].add(rLiquidity);
        if(_isExcluded[address(this)])
            _tOwned[address(this)] = _tOwned[address(this)].add(tLiquidity);
    }
 
    function calculateTaxFee(uint256 _amount) private view returns (uint256) {
        return _amount.mul(_taxFee).div(
            10**2
        );
    }
 
    function calculateLiquidityFee(uint256 _amount) private view returns (uint256) {
        return _amount.mul(_liquidityFee).div(
            10**2
        );
    }
 
    function removeAllFee() private {
        if(_taxFee == 0 && _liquidityFee == 0) return;
 
        _previousTaxFee = _taxFee;
        _previousLiquidityFee = _liquidityFee;
 
        _taxFee = 0;
        _liquidityFee = 0;
    }
 
    function restoreAllFee() private {
        _taxFee = _previousTaxFee;
        _liquidityFee = _previousLiquidityFee;
    }
 
    function isExcludedFromFee(address account) public view returns(bool) {
        return _isExcludedFromFee[account];
    }
 
    function excludeFromFee(address account) public onlyOwner {
        _isExcludedFromFee[account] = true;
    }
 
    function includeInFee(address account) public onlyOwner {
        _isExcludedFromFee[account] = false;
    }
 
    function setTaxFeePercent(uint256 taxFee) external onlyOwner() {
        _taxFee = taxFee;
    }
 
    function setLiquidityFeePercent(uint256 liquidityFee) external onlyOwner() {
        _liquidityFee = liquidityFee;
    }
 
    function setMaxTxAmount(uint256 maxTxAmount) external onlyOwner() {
        _maxTxAmount = maxTxAmount;
    }
 
    function setMarketingDivisor(uint256 divisor) external onlyOwner() {
        marketingDivisor = divisor;
    }
 
    function setNumTokensSellToAddToLiquidity(uint256 _minimumTokensBeforeSwap) external onlyOwner() {
        minimumTokensBeforeSwap = _minimumTokensBeforeSwap;
    }
 
     function setBuybackUpperLimit(uint256 buyBackLimit) external onlyOwner() {
        buyBackUpperLimit = buyBackLimit * 10**18;
    }
 
    function setMarketingAddress(address _marketingAddress) external onlyOwner() {
        marketingAddress = payable(_marketingAddress);
    }
 
    function setSwapAndLiquifyEnabled(bool _enabled) public onlyOwner {
        swapAndLiquifyEnabled = _enabled;
        emit SwapAndLiquifyEnabledUpdated(_enabled);
    }
 
    function setBuyBackEnabled(bool _enabled) public onlyOwner {
        buyBackEnabled = _enabled;
        emit BuyBackEnabledUpdated(_enabled);
    }
 
    function prepareForPreSale() external onlyOwner {
        setSwapAndLiquifyEnabled(false);
        _taxFee = 0;
        _liquidityFee = 0;
        _maxTxAmount = 1000000000 * 10**6 * 10**9;
    }
 
    function afterPreSale() external onlyOwner {
        setSwapAndLiquifyEnabled(true);
        _taxFee = 2;
        _liquidityFee = 8;
        _maxTxAmount = 3000000 * 10**6 * 10**9;
    }
 
    function transferToAddressETH(address payable recipient, uint256 amount) private {
        recipient.transfer(amount);
    }
 
     //to recieve ETH from uniswapV2Router when swaping
    receive() external payable {}
}

I only import the libraries with import keyword (the smart contract code is the same of pastebin).

Best Answer

Related Solutions

Solidity – Purpose of Declaring Router Address in a Solidity Constructor

ERC-20 Deployment on Testnet – Fixing Deployment Issues with Uniswap Router

Related Topic