All Questions
15 questions
0
votes
1
answer
39
views
Can transactions sent later have a lower block number?
I apologize in advance if my question is stupid.
What I'm curious about is that transactions sent first must be recorded in the preceding block number?
As far as I know, just because you enter the ...
- 61
0
votes
1
answer
863
views
Can a contract create a transaction that may trigger a change of state on ethereum network?
I am looking at the slides of this link. As I see there the author differentiates between a message and a transaction. As can be depicted in this slide
Furthermore, looking at the four cases of ...
- 287
2
votes
0
answers
1k
views
Exchange deposits using smart contracts and externally owned accounts
While researching how different exchanges handle user deposits, I noticed a stark contrast between several prominent exchanges.
Kraken:
Exchanges like Kraken use newly generated deposit addresses (no ...
- 191
1
vote
1
answer
107
views
Gas cost for contract transaction called form external
If I call my contract and ask it to send x amount of ether to another account y, I know i have to pay a transaction cost.
Will the contract also have to pay any amount while sending the ether to the ...
- 147
0
votes
1
answer
70
views
How to make transaction of some ether in Buyer Seller type of contract?
In this I have set modifier (msg.sender == sellerAddress) which is not valid.
But in this scenario, I want to allow only and only sellerAddress to take ether from my contract. How can I allow only ...
- 417
3
votes
1
answer
1k
views
Send eth from one account to another using transfer() function
I am trying to write a smart contract that will send eth from one account to another account :
Contract Send {
event Sent(address from, address to, uint amount );
function send(address _receiver,...
- 31
0
votes
1
answer
124
views
Transfer event for zero amount
Should I emit Transfer event, when zero amount of Ether or of a token is transferred?
Variants of the answer:
yes
no
both are OK
- 1,854
0
votes
1
answer
60
views
How to send a token with Ether? (several variants)
I want to sell my token to users paying by Ether.
Is it a good idea to require the user to pass his wallet (to receive) Ether as the EVM payload?
Or is it needed to have my private key uploaded to ...
- 1,854
1
vote
1
answer
177
views
How to calculate exchange fee in ETH in transaction?
Let's say I have the following decoded transaction input data:
[
"0x0000000000000000000000000000000000000000",
"690000000000000000",
"0xac709fcb44a43c35f0da4e3163b117a17f3770f5",
"...
- 325
2
votes
1
answer
91
views
How to calculate number of ETH that got bought in transaction by trading?
Let's say I have the following decoded transaction input data:
[
"0xac709fcb44a43c35f0da4e3163b117a17f3770f5",
"2500000000000000000000",
"0x0000000000000000000000000000000000000000",
...
- 325
0
votes
1
answer
372
views
Withdrawing ethereum from a smart contract (return to sender)
Let's say I have a decentralized application that allows people to buy some object at an arbitrary price.
User 1 purchases the object for 1 eth. A few moments later, user 2 purchases the same item. ...
- 169
0
votes
0
answers
235
views
How to call hash function in solidity to free a stuck smart contract?
I was selling an altcoin on Etherdelta using a sell order and 3 transactions went through however the ethereum did not show up in my wallet. I contacted support and they say that "your altcoin is ...
- 1
0
votes
1
answer
69
views
Purchase Ethereum for rewarding users
How can I purchase some Ethereum so that I can award it to our users for winning quiz. I am thinking of making a system where we can invoke RPC calls like this:
curl -d '{"jsonrpc":"2.0","method":"...
- 227
2
votes
1
answer
127
views
Watching the transaction of an external account using smart contract
Is their any way to execute a function of smart contract whenever a transaction to a predefined external account occurs? I mean if someone transfers some ethers to account A, a function of a smart ...
- 3,545
8
votes
2
answers
2k
views
Smart contract based betting — protection against depreciation
Let’s say I want to enter into a bet with my friend — if it rains 10 days from now, I will pay him $100; if it doesn’t, he will pay me $100.
Would it be possible to take advantage of smart contract ...
- 309