How to compare hash of two structures?

Question

function checkOffers() public returns (bool){
    uint256 a = sha256(offerFromProducer);
    uint256 b = sha256(offerFromConsumer);
    if(a == b){
        return true;
    }
    return false;
}

Is there some method to compare two structs in Solidity?

Answer 1

The return value of sha256 is bytes32. So use bytes32 a = sha256(...) and do the same for b. This will fix the compiler errors and a == b will work.

But currently you cannot pass a struct to hashing functions like sha256, keccak256: https://github.com/ethereum/solidity/issues/980. So generally the members of the structs have to be compared against each other. A more specific question may help to uncover possible optimizations (for example, there may be ways to reduce the comparisons required depending on the app design).