Solidity: Is there a way to get the timestamp of a transaction that executed?

Question

Is there a way for a contract to be able to get the exact time someone called a function in it?

For example, if someone sends funds to the contract address, is there a timestamp recorded by the blockchain that would give the received time of this transaction?

And if so, how would I get this value in Solidity and would the timestamp of this transaction be modifiable by the user in any kind of way once it is sent?

Answer 1

A transaction doesn't have a timestamp. However, every block provides a timestamp (when it was collected), but if the time is critical for you, don't refer to this timestamp because a miner could modify it by about 900s. Instead, you could use block.number.

1- current block timestamp is returned by now:

e.g.

contract Test {
    function Time_call() returns (uint256){
        return now;
    }
}

Time_call() will return something like 1478431966 (which you could convert into a readable form in https://www.unixtimestamp.com/).

2- block number is returned using block.number:

 function Time_call() returns (uint256){
        return block.number; 
    }

to get the call time, you could use the block.number and the block time (an average).

Edit: if you want when the transaction was sent, use JavaScript in your Dapp to get the current time var seconds = new Date().getTime(); and send it in the data field within your transaction.

Answer 2

You can use block.timestamp to get the current block timestamp

Reference:

Solidity Docs

Answer 3

You can simply use the keyword now to get the current timestamp.

Answer 4

below code will store time at which updateTime() is called, and get that call time by getTime.

contract calculateTime{
    uint calcTime=0;
    function updateTime() public{
        calcTime=block.timestamp;
    }
    function getTime() public view returns(uint){
        return calcTime;
    }
}

Answer 5

pragma solidity ^0.8.9;

contract Time{

   uint public blockTime;

    function getCurrentTime() public {
        blockTime = block.timestamp;
    }

}