I'm getting this error when trying to compile a contract using cmd on windows:

Error parsing C:/Users/alexa/Desktop/contracts/contracts/ApprovalContract.sol: ParsedContract.sol:6:37: ParserError: Expected primary expression.

address public constant approver = ;

            ^ Compilation failed. See above.

Truffle v5.0.0 (core: 5.0.0)

Node v10.15.0

Here's the contract

pragma solidity ^0.4.18;

contract ApprovalContract {

    address public sender;
    address public receiver;
    address public constant approver = ;

    function deposit(address_receiver) external payable {
        require(msg.value > 0);
        sender = msg.sender;
        receiver = _receiver;

    function viewApprover() external pure returns(address) {

    function approve() external {
        require(msg.sender == approver);
  • I'm voting to close this question as off-topic because it looks like a deliberate syntax error, followed by "what's wrong with this code?". – goodvibration Dec 31 '18 at 8:05

This line is invalid

address public constant approver = ;

Try replacing it with something like this:

address public approver;
  • Thank you abed, I've noticed that I was missing the actual 0x address after the equal sign. Also on: function deposit(address_receiver) external payable { where it should be function deposit(address _receiver) external payable { missing a space there. – Arturo Heredia Dec 30 '18 at 23:37

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