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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?

Pabi
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5 Answers5

24

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.

Badr Bellaj
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  • @Badr_Bellaj if I am not mistaking, this returns the timestamp of the block and not of the time the transaction was received/sent. Am I correct? Because what I need is to get the time the transaction was sent not the time it was executed at. – Pabi Nov 06 '16 at 13:18
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    it is impossible to get when the transaction was sent, there is no timestamp in the transaction. besides, we don't know how time it was on the pool or when it was signed. However you could write a dapp using web3js which send such information withing the transaction. – Badr Bellaj Nov 06 '16 at 13:27
  • check the edit for more details – Badr Bellaj Nov 06 '16 at 13:39
  • @Badr_Bellaj How do you then interact with data in the data field in solidity? – Pabi Nov 06 '16 at 13:41
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    by using msg.data – Badr Bellaj Nov 06 '16 at 13:53
  • read also http://ethereum.stackexchange.com/questions/2205/how-to-convert-msg-data-to-a-uint – Badr Bellaj Nov 06 '16 at 14:31
  • Thanks for your answer. It is important for us to remember that if we want to send timestamp from Javascript to solidity, we will need to convert it into seconds like so var seconds = new Date().getTime() / 1000;. this will not work var seconds = new Date().getTime(). Hope this helps – AllJs Nov 09 '22 at 22:53
1

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

Reference:

Solidity Docs

Harshana
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0

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

Richard Bonneau
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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;
    }
}
aakash4dev
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0
pragma solidity ^0.8.9;

contract Time{

   uint public blockTime;

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

}
Ismael
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Abhinav Krishna
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