Warning: This declaration shadows an existing declaration

Question

Can you please help me out with this code, where I get the six warnings shown bellow? As a result, the withdrawal doesn't go through with the specified amount. But I don't know how to get around it. This code same in Analogy would in Python for sure.

And a secondary question, why does hardhat/console.sol work in Remix only on local blockchain, but not when I deploy it Goerli for example?

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.17;

import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "hardhat/console.sol";
import "https://github.com/f22daniel/helpful_smart_contracts
        /blob/main/GoerliPriceFeedV2.sol";

contract SimpleExchange is ReentrancyGuard{
address owner;
address priceFeedContract;
event Transaction(address _from, address _to, uint transactDate, uint _amount, string currency);
User[] public user;
struct User {
    address account;
    uint date;
    uint amount;
}

constructor() {
    priceFeedContract = 0x99479b65dCCB46AdfB55B04822BFb1A09944295f;
    owner = msg.sender;
    console.log("View transaction");
}

function usdWeiConverter(uint _amount) public view returns(uint) {
    uint priceEthUsd = GoerliPriceConsumerV3(priceFeedContract).UintEthUsd() * 10**10;
    uint amount = _amount * 10**18;
    uint ethAmountSent = (amount * 10**18)/priceEthUsd;
    return ethAmountSent;
}
function czkUsdConverter(uint _amount) public view returns(uint) {
    uint priceCzkUsd = (10**18 / GoerliPriceConsumerV3(priceFeedContract).UintCzkUsd() * 10**18) / 10**26;
    uint usdAmount = _amount * 100 / priceCzkUsd;
    return usdAmount;
}
function jpyUsdConverter(uint _amount) public view returns(uint) {
    uint priceJpyUsd = (10**18 / GoerliPriceConsumerV3(priceFeedContract).UintJpyUsd() * 10**18) / 10**18;
    uint jpyAmount = _amount / priceJpyUsd;
    return jpyAmount;
}

function sendEthViaUsd(uint _amount) public payable {
    bool sent = false;
    uint amount = msg.value;
    uint requiredAmount = usdWeiConverter(_amount);
    require(_amount >= 20, "Min. $20 needed");
    require(amount >= requiredAmount, "User needs to send higher ETH value.");
    for (uint i = 0; i < user.length; ++i){
        User storage _user = user[i];
        if (_user.account == msg.sender) {
            _user.amount += msg.value - (amount - requiredAmount);
            payable(msg.sender).transfer(amount - requiredAmount);
            sent = true;
            emit Transaction(msg.sender, address(this), block.timestamp, (msg.value - (amount - requiredAmount)), "USD");
            require(sent, "Transaction failed!");
            return ;
        }
    }
    payable(msg.sender).transfer(amount - requiredAmount);
    user.push(User(msg.sender, block.timestamp, (msg.value - (amount - requiredAmount))));
    sent = true;
    emit Transaction(msg.sender, address(this), block.timestamp, (msg.value - (amount - requiredAmount)), "USD");
    require(sent, "Transaction failed!");
}
function sendEthViaCzk(uint _amount) public payable {
    bool sent = false;
    uint amount = msg.value;
    uint CzkUsdCost = czkUsdConverter(_amount);
    uint requiredAmount = usdWeiConverter(CzkUsdCost);
    require(_amount >= 800, "Min. 800 CZK needed");
    require(amount >= requiredAmount, "User needs to send higher ETH value.");
    for (uint i = 0; i < user.length; ++i){
        User storage _user = user[i];
        if (_user.account == msg.sender) {
            _user.amount += msg.value - (amount - requiredAmount);
            payable(msg.sender).transfer(amount - requiredAmount);
            sent = true;
            emit Transaction(msg.sender, address(this), block.timestamp, (msg.value - (amount - requiredAmount)), "USD");
            require(sent, "Transaction failed!");
            return ;
        }
    }
    payable(msg.sender).transfer(amount - requiredAmount);
    user.push(User(msg.sender, block.timestamp, (msg.value - (amount - requiredAmount))));
    sent = true;
    emit Transaction(msg.sender, address(this), block.timestamp, (msg.value - (amount - requiredAmount)), "USD");
    require(sent, "Transaction failed!");
}
function sendEthViaJpy(uint _amount) public payable {
    bool sent = false;
    uint amount = msg.value;
    uint JpyUsdCost = jpyUsdConverter(_amount);
    uint requiredAmount = usdWeiConverter(JpyUsdCost);
    require(_amount >= 2800, "Min. 2 800 JPY needed");
    require(amount >= requiredAmount, "User needs to send higher ETH value.");

    for (uint i = 0; i < user.length; ++i){
        User storage _user = user[i];
        if (_user.account == msg.sender) {
            _user.amount += msg.value - (amount - requiredAmount);
            payable(msg.sender).transfer(amount - requiredAmount);
            sent = true;
            emit Transaction(msg.sender, address(this), block.timestamp, (msg.value - (amount - requiredAmount)), "USD");
            require(sent, "Transaction failed!");
            return ;
        }
    }
    payable(msg.sender).transfer(amount - requiredAmount);
    user.push(User(msg.sender, block.timestamp, (msg.value - (amount - requiredAmount))));
    sent = true;
    emit Transaction(msg.sender, address(this), block.timestamp, (msg.value - (amount - requiredAmount)), "USD");
    require(sent, "Transaction failed!");
}

function withdraw(uint _amount, string calldata _currency) external nonReentrant {
    bool sent = false;
    uint withdrawAmount;
    if (keccak256(abi.encode(_currency)) == keccak256(abi.encode("USD"))){
        uint withdrawAmount = usdWeiConverter(_amount);
    }
    else if (keccak256(abi.encode(_currency)) == keccak256(abi.encode("CZK"))){
        uint CzkUsdConversion = czkUsdConverter(_amount);
        uint withdrawAmount = usdWeiConverter(CzkUsdConversion);
    }
    else if (keccak256(abi.encode(_currency)) == keccak256(abi.encode("JPY"))){
        uint JpyUsdConversion = jpyUsdConverter(_amount);
        uint withdrawAmount = usdWeiConverter(JpyUsdConversion);
    }
    else {
        revert("Currency has to be USD, CZK or JPY");
    }

    for (uint i = 0; i <= user.length; ++i) {
        User storage _user = user[i];
        if (_user.account == msg.sender) {
            require(withdrawAmount <= _user.amount, "Not enough funds!");
            payable(msg.sender).transfer(withdrawAmount);
            _user.amount -= withdrawAmount; 
            // user[i] = user[user.length - 1];
            // user.pop();
            sent = true;
            return ;
        }
    }
    require(sent, "Withdrawal failed");
}
function withdrawAll() external {
    require(msg.sender == owner, "Not owner!");
    payable(msg.sender).transfer(address(this).balance);
}
}

Answer 1

You already declared withdrawAmount line 117. Just remove the uint identifier before the 2nd, 3rd and 4th withdrawAmount.