Can anyone explain this function and significance of 86400?

Question

I have a function which is used to check if 90 days have been passed or not after staking, but I can't figure out why 86400 is mentioned, like is it seconds or minutes or anything else and how can I change that 90 days to any other value of my choice.

        function getTimePassedSinceStake(address _owner, uint256 _index)
        public
        view
        returns (uint256)
    {
        return (block.timestamp - userInfo[_owner][_index].stakeTime) / 86400;
    }

Answer 1

From the documentation :

block.timestamp (uint): current block timestamp as seconds since unix epoch

So :

block.timestamp - userInfo[_owner][_index].stakeTime

Is the number of seconds between stakeTime and block.timestamp. Dividing by 86400 is dividing by the number of seconds in a day (60 seconds * 60 minutes * 24 hours = 86400)

 return (block.timestamp - userInfo[_owner][_index].stakeTime) / 86400;

returns the number of whole days between stakeTime and block.timstamp this has nothing to do with 90 days here.

An alternative syntax could be :

return (block.timestamp - userInfo[_owner][_index].stakeTime) / 1 days;

---

how can I change that 90 days to any other value of my choice.

I found a contract with the same code here, that has the following unstake function with a 1 day limit :

function unStake(uint256 _index) external {
    address unStaker = msg.sender;
    UserInfo storage userDetails = userInfo[unStaker][_index];
    uint256 tokenId1 = userDetails.tokenId1;
    uint256 timePassedSinceStaked = getTimePassedSinceStake(
        unStaker,
        _index
    );
    require(
        timePassedSinceStaked >= 1,
        "You can not unstake before 1 day"
    );
    userDetails = userInfo[unStaker][userInfo[unStaker].length - 1];
    userInfo[unStaker].pop();

    ERC721.safeTransferFrom(address(this), unStaker, tokenId1, "");
   

    GemToken.claimByLuckyDragon(unStaker, 0);
    emit UnStakedLuckyDragon(
        unStaker,
        tokenId1,
        block.timestamp
    );
}

Here it is limiting to 1 day of waiting time, by changing :

require(
    timePassedSinceStaked >= 1,
    "You can not unstake before 1 day"
);

to :

require(
    timePassedSinceStaked >= 90,
    "You can not unstake before 90 day"
);

It would require 90 days, of course you can set the value of your choice.

I hope that answers your question.

Answer 2

ETH contracts use Unix time:

https://www.epochconverter.com The Unix epoch (or Unix time or POSIX time or Unix timestamp) is the number of seconds that have elapsed since January 1, 1970 (midnight UTC/GMT)