How can i send back the ether which i used to buy a token in ERC20?

Question

Iam trying to write method in solidity where it checks if the given ether is enough to buy my coin. If its enough I will give them the respective amount of coins but if the ether is not enough I need to send back the ether which is getting used to buy a coin. Is there any method to do that ?

This is the method i have written to buy a coin.

function buyTokens(uint256 noOfCoins) public payable returns (bool success){
    if(CoinValue*noOfCoins <= msg.value)
    {
        balances[msg.sender] += noOfCoins;
        return true;
    }
    else{

        emit TokenIssues("You doesnt have enough balances to purchase these quartz base coins");
        msg.sender.transfer(msg.value);
        return false;
    }
}

Answer 1

If the msg.value is lower then the amount you are expecting just throw in the else clause. That way the ether will be returned to the user.