Handle exchanging 6 Decimal Token to 18 Decimal Token (eg. USDC to ERC20)

Question

I am trying to learn Solidity and write a contract that accepts USDC for my token which has 18 decimals.

I'm getting confused as how to treat the amount being sent when I buy my ERC20.

eg.

function buyToken(IERC20 token, uint256 amount) public payable

Where token is the address of USDC and amount is the total USDC I will pay/exchange for my ERC20 Token. Should I convert the amount provided (6 decimals) to 18 decimals? How? What is the best practice for this?

Answer 1

Since in your case, the token is of 18 decimals, suppose you want to buy 10 tokens so the amount that you would enter is 10 multiplied by 10^18 which means 10000000000000000000. Alternatively you can code your function so that the user enters the actual amount which is 10 and inside the function the amount is multiplied by 10^18 so that no body has to count the number of zeros to append to.

so the above function would become

function buyToken(IERC20 token, uint256 amount) public payable {
uint _amount = amount * (10**18)

****rest of the logic****
}

Answer 2

I solved it as follows

function getLastestPrice() public view returns (uint) {
    (, int256 price, , , ) = priceFeed.latestRoundData();

    uint adjustmentPrice = uint(price) / 10**8;
    return adjustmentPrice;
}