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1500 questions
12
votes
3 answers
What is the regex to validate an Ethereum transaction hash?
I am building an application which requires user to paste the transaction hash of a transaction. But i want a regex string i could pass to the pattern attribute of the input element that receives it to validate it.
What is the general regexp that…
Oluwatumbi
- 223
- 1
- 2
- 6
12
votes
1 answer
What if difficulty bomb makes mining impossible before POS release?
As mining difficulty raises and POS is still not ready, I was just wondering if POS release can still be on time compared to the difficulty bomb giving too high difficulty. In simpler words, is there a risk that difficulty become too high to mine…
Nicolas Massart
- 6,783
- 2
- 29
- 63
12
votes
2 answers
What is an HD wallet for Ether and how to create one using node.js?
I know the basics of blockchain and how to use geth. However, I'm curious to know how to build a wallet using nodejs. What I understand is that you can create a account using geth console (private network) to work on and when pass command…
Shivam Nema
- 123
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12
votes
6 answers
How to check the size of a contract in Solidity?
I want to measure the size of my compiled contract using solc.
I can dump the binary using --bin or --bin-runtime and then count how many hexadecimal digits it contains.
Is there an easier way to do it?
Shuzheng
- 1,855
- 3
- 19
- 31
12
votes
2 answers
get the return value of payable function?
Let's say there's a payable Solidity function
function doSomething()
payable
returns(uint)
{
require(msg.value == 1 ether);
return 1;
}
And you call this function
instance.doSomething({
from:_account,
value:1 ether
…
coindevbw
- 121
- 1
- 3
12
votes
1 answer
How to deploy contracts that take parameters in their initialisers using Truffle?
I'm trying to build a smart contract with Truffle. I can compile it just fine, but when I try to deploy it on the network, I don't get an option to pass in the initialiser parameters and thus the contract fails.
How do I pass the parameters to a…
ThePiachu
- 562
- 1
- 6
- 14
12
votes
3 answers
Geth response: invalid content type, only application/json is supported
I started geth on a remote server running on rinkeby with the parameters --rinkeby --fast --cache=128 --rpc --rpcaddr 0.0.0.0
When I try to test my access to geth using
curl -X POST --data…
Athena Wisdom
- 269
- 1
- 2
- 12
12
votes
1 answer
How growing contract storage increases the gas spending?
I have some further questions about this and this threads.
For simplicity, let's imagine that I want to create a cryptocurrency on top of ethereum.
The contract that "handles" this cryptocurrency will have a mapping that will associate addresses to…
Henrique Barcelos
- 2,481
- 4
- 20
- 38
12
votes
3 answers
Using require or modifier?
If you create a function that you only want the owner to interact with
would you use
require(msg.sender == owner)
or
modifier onlyOwner() {
require(msg.sender == owner);
_;
}
Which would be the most cost efficient for smart contracts,…
JorahFriendzone
- 517
- 1
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- 22
12
votes
1 answer
How to generate sugared assembly code from Solidity code?
In the Solidity documentation I see a sample assembly code:
{
mstore(0x40, 0x60) // store the "free memory pointer"
// function dispatcher
switch div(calldataload(0), exp(2, 226))
case 0xb3de648b {
let (r) = f(calldataload(4))
let…
medvedev1088
- 10,996
- 5
- 35
- 63
12
votes
2 answers
Does knowing half private key provide any useful information?
I have a private key and I want to store a paper version of it. I would like to split it in 2 equal parts (first 32 numbers and last 32 numbers) and store them in 2 different locations.
Let's assume I'm 100% sure no one can access both parts, but…
AnotherUser
- 223
- 2
- 8
12
votes
2 answers
Finding and Using Solidity Libraries (ie. Math functions)
How do I find and use any existing Solidity libraries like you might in Javascript?
For example, Math functions: How do I implement the equivalent of Math.sqrt(x) in a solidity function?
Related: What is --libraries doing in that second question…
Bill LaPrise
- 683
- 8
- 17
12
votes
3 answers
What uint type should be declared for unix timestamps?
I try to specify uint type to uint16 instead of just doing uint or uint256 when dealing with time stamps but it says that I must use at least uint24. It works with uint24, but shouldn't uint16 be plenty enough?
NowsyMe
- 1,365
- 1
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- 37
12
votes
1 answer
Is there any profit from using pure and view functions modifiers?
I have a function that does not read or modify contract's state:
contract C {
function add(uint a, uint b) public returns (uint) {
uint res = a + b;
return res;
}
}
Does it make sense to use pure/view modifier? I mean,…
30mb1
- 369
- 3
- 8
12
votes
2 answers
Should I use 'bytes' or 'string' always?
So after my understandings, bytes and strings are basically doing the same just in different formats and using bytes is cheaper -leading to my question, should I then only use string for data that is longer than 32 bytes and specify byte type for…
6egic
- 1,327
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- 17