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I'm new in the solidity coding. I'm trying to retrieve the unsold tokens from a crowdsale contract. I add the command tokenReward.transfer(beneficiary, amountRaised);

pragma solidity ^0.4.20;

interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) public; }

contract RS1 {
    // Public variables of the token
    string public name;
    string public symbol;
    uint8 public decimals = 0;
    // 18 decimals is the strongly suggested default, avoid changing it
    uint256 public totalSupply;

    // This creates an array with all balances
    mapping (address => uint256) public balanceOf;
    mapping (address => mapping (address => uint256)) public allowance;

    // This generates a public event on the blockchain that will notify clients
    event Transfer(address indexed from, address indexed to, uint256 value);

    // This notifies clients about the amount burnt
    event Burn(address indexed from, uint256 value);

    /**
     * Constrctor function
     *
     * Initializes contract with initial supply tokens to the creator of the contract
     */
    function RS1(
    ) public {
        totalSupply = 100000;  // Update total supply with the decimal amount
        balanceOf[msg.sender] = totalSupply;                // Give the creator all initial tokens
        name = "RS1";                                   // Set the name for display purposes
        symbol = "RS1";                               // Set the symbol for display purposes
    }

    /**
     * Internal transfer, only can be called by this contract
     */
    function _transfer(address _from, address _to, uint _value) internal {
        // Prevent transfer to 0x0 address. Use burn() instead
        require(_to != 0x0);
        // Check if the sender has enough
        require(balanceOf[_from] >= _value);
        // Check for overflows
        require(balanceOf[_to] + _value > balanceOf[_to]);
        // Save this for an assertion in the future
        uint previousBalances = balanceOf[_from] + balanceOf[_to];
        // Subtract from the sender
        balanceOf[_from] -= _value;
        // Add the same to the recipient
        balanceOf[_to] += _value;
        Transfer(_from, _to, _value);
        // Asserts are used to use static analysis to find bugs in your code. They should never fail
        assert(balanceOf[_from] + balanceOf[_to] == previousBalances);
    }

    /**
     * Transfer tokens
     *
     * Send `_value` tokens to `_to` from your account
     *
     * @param _to The address of the recipient
     * @param _value the amount to send
     */
    function transfer(address _to, uint256 _value) public {
        _transfer(msg.sender, _to, _value);
    }

    /**
     * Transfer tokens from other address
     *
     * Send `_value` tokens to `_to` on behalf of `_from`
     *
     * @param _from The address of the sender
     * @param _to The address of the recipient
     * @param _value the amount to send
     */
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
        require(_value <= allowance[_from][msg.sender]);     // Check allowance
        allowance[_from][msg.sender] -= _value;
        _transfer(_from, _to, _value);
        return true;
    }

    /**
     * Set allowance for other address
     *
     * Allows `_spender` to spend no more than `_value` tokens on your behalf
     *
     * @param _spender The address authorized to spend
     * @param _value the max amount they can spend
     */
    function approve(address _spender, uint256 _value) public
        returns (bool success) {
        allowance[msg.sender][_spender] = _value;
        return true;
    }

    /**
     * Set allowance for other address and notify
     *
     * Allows `_spender` to spend no more than `_value` tokens on your behalf, and then ping the contract about it
     *
     * @param _spender The address authorized to spend
     * @param _value the max amount they can spend
     * @param _extraData some extra information to send to the approved contract
     */
    function approveAndCall(address _spender, uint256 _value, bytes _extraData)
        public
        returns (bool success) {
        tokenRecipient spender = tokenRecipient(_spender);
        if (approve(_spender, _value)) {
            spender.receiveApproval(msg.sender, _value, this, _extraData);
            return true;
        }
    }

    /**
     * Destroy tokens
     *
     * Remove `_value` tokens from the system irreversibly
     *
     * @param _value the amount of money to burn
     */
    function burn(uint256 _value) public returns (bool success) {
        require(balanceOf[msg.sender] >= _value);   // Check if the sender has enough
        balanceOf[msg.sender] -= _value;            // Subtract from the sender
        totalSupply -= _value;                      // Updates totalSupply
        Burn(msg.sender, _value);
        return true;
    }

    /**
     * Destroy tokens from other account
     *
     * Remove `_value` tokens from the system irreversibly on behalf of `_from`.
     *
     * @param _from the address of the sender
     * @param _value the amount of money to burn
     */
    function burnFrom(address _from, uint256 _value) public returns (bool success) {
        require(balanceOf[_from] >= _value);                // Check if the targeted balance is enough
        require(_value <= allowance[_from][msg.sender]);    // Check allowance
        balanceOf[_from] -= _value;                         // Subtract from the targeted balance
        allowance[_from][msg.sender] -= _value;             // Subtract from the sender's allowance
        totalSupply -= _value;                              // Update totalSupply
        Burn(_from, _value);
        return true;
    }
}

and below the crowdsale

pragma solidity ^0.4.16;

interface token {
    function transfer(address receiver, uint amount);
}

contract CRD2 {
address public beneficiary;
uint public fundingGoal;
uint public amountRaised;

uint public amountToken;

uint public deadline;
uint public price;
token public tokenReward;
mapping(address => uint256) public balanceOf;
bool fundingGoalReached = false;
bool crowdsaleClosed = false;
event GoalReached(address recipient, uint totalAmountRaised);
event FundTransfer(address backer, uint amount, bool isContribution);

event TokenTransfer(address backer, uint amountToken, bool isContribution);

/**
 * Constrctor function
 *
 * Setup the owner
 */
function CRD2(
    address ifSuccessfulSendTo,
    uint fundingGoalInEthers,
    uint durationInMinutes,
    uint etherCostOfEachToken,
    address addressOfTokenUsedAsReward
) {
    beneficiary = 0xAb44F092f1E01E8f91DfE9035A09461B928eDFb7;
    fundingGoal = 0.1 * 1 ether;
    deadline = now + 10 * 1 minutes;
    price = 0.1 * 1 ether;
    tokenReward = token(0x390fc971502fb5236570ba28c81e0Ba71AC55910);
}

/**
 * Fallback function
 *
 * The function without name is the default function that is called whenever anyone sends funds to a contract
 */
function () payable {
    require(!crowdsaleClosed);
    uint amount = msg.value;
    balanceOf[msg.sender] += amount;
    amountRaised += amount;
    tokenReward.transfer(msg.sender, amount / price);
    FundTransfer(msg.sender, amount, true);
}

modifier afterDeadline() { if (now >= deadline) _; }

/**
 * Check if goal was reached
 *
 * Checks if the goal or time limit has been reached and ends the campaign
 */
function checkGoalReached() afterDeadline {
    if (amountRaised >= fundingGoal){
        fundingGoalReached = true;
        GoalReached(beneficiary, amountRaised);
    }
    crowdsaleClosed = true;
}


/**
 * Withdraw the funds
 *
 * Checks to see if goal or time limit has been reached, and if so, and the funding goal was reached,
 * sends the entire amount to the beneficiary. If goal was not reached, each contributor can withdraw
 * the amount they contributed.
 */
function safeWithdrawal() afterDeadline {
    if (!fundingGoalReached) {
        uint amount = balanceOf[msg.sender];
        balanceOf[msg.sender] = 0;
        if (amount > 0) {
            if (msg.sender.send(amount)) {
                FundTransfer(msg.sender, amount, false);
            } else {
                balanceOf[msg.sender] = amount;
            }
        }
    }

    if (fundingGoalReached && beneficiary == msg.sender) {
        if (beneficiary.send(amountRaised)) {
            FundTransfer(beneficiary, amountRaised, false);
            TokenTransfer(beneficiary, amountToken, false);
        } else {
            //If we fail to send the funds to beneficiary, unlock funders balance
            fundingGoalReached = false;
        }
    }
}

}

but it doesn't work. Is there someone could help me? Thanks

  • 1
    There seems to be some confusion between tokens and ether... amountRaised is used as the amount of ether transferred as well as the amount of tokens transferred. It seems that one of those must be wrong. – user19510 Mar 7 '18 at 21:34
  • Thank you, I think you may be right. Do you have any suggestion to receive the unsold tokens? tks – Ferdinando Cantarelli Mar 7 '18 at 21:41
  • Do you have a variable that keeps track of how many tokens are unsold? – user19510 Mar 7 '18 at 21:42
  • no... What kind of variable I could put in the code to keep track of this? – Ferdinando Cantarelli Mar 8 '18 at 20:01
  • @Rajesh's answer is a good way to go without adding a variable. Just transfer the remaining balance. – user19510 Mar 8 '18 at 20:12
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It should be like this. This transfer all remaining tokens in the contract to the beneficiary(msg.sender in this case).

tokenReward.transfer(beneficiary, tokenReward.balanceOf(this));

Edit

Have the following line of code added in the token interface

function balanceOf(address _owner);
  • I tried but When I compile it I receive the error message "Memeber "balanceOf" not found or not visible after the argument-dependent lookup in contract token". – Ferdinando Cantarelli Mar 8 '18 at 20:03
  • have edited the answer, Try now. – Rajesh Mar 9 '18 at 4:55

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