Are there null like thing in solidity

Question

    struct buyer{
       uint amount;
       Status status;
    }

    mapping(address=>buyer) public buyers;
    mapping(uint=>address) buyerIndex;
    uint publi         


        

Answer 1

In solidity every variable is set to 0 by default.

You should think of mappings as all possible combinations are set to 0 by default.

In your specific case I would use the following:

if (buyers[msg.sender].amount == 0)