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1500 questions
33
votes
1 answer
How does the solidity optimizer work?
The compiler for solidity supports the flag --optimize which performs some set of optimizations to the compiled solidity code, typically resulting in a reduction of gas costs.
How does the optimizer work and what are some examples of the…
Piper Merriam
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33
votes
5 answers
How can I sign a piece of data with the private key of an Ethereum address?
I would like to use the key pair of one of my Ethereum accounts to sign a piece of data. How can this be done?
Piper Merriam
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33
votes
3 answers
TypeError: Data location must be "storage" or "memory" for parameter in function, but none was given
/// @dev Adds a new transaction to the transaction mapping, if transaction does not exist yet.
/// @param destination Transaction target address.
/// @param value Transaction ether value.
/// @param data Transaction data payload.
/// @return Returns…
CryptoScroller
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33
votes
9 answers
How do I get the raw private key from my Mist keystore file?
I use the Mist wallet.
I would like to know:
How I can get the private key of my account.
How I can use this private key to sign messages.
Wang
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33
votes
1 answer
What is coinbase?
What is the ethereum coinbase? I understand it is an account, but what makes it different? Is it the same as Etherbase?
I've read it's the "default account for your console session."
Does that mean, when I interact with a dApp in Mist, this is the…
max
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33
votes
3 answers
Can I save structs in a Mapping?
Is it possible to store structs in a Mapping or any dynamic memory structure in my Solidity SmartContract?
arodriguezdonaire
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33
votes
8 answers
What are the development tools for Ethereum?
Could someone make a list with development tools for Ethereum together with a short description what they are good for?
mKoeppelmann
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33
votes
3 answers
What is the 'this' keyword in Solidity?
What is the specification of the 'this' keyword in Solidity?
How does it work?
Sample code from Solidity Features · ethereum/wiki Wiki
contract Helper {
function getBalance() returns (uint bal) {
return this.balance; // balance is "inherited"…
Satoshi Nakanishi
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32
votes
4 answers
Visibility for constructor is ignored. If you want the contract to be non-deployable, making it "abstract" is sufficient
What does this warning actually mean and how to resolve this ?
Lokesh Mishra
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32
votes
5 answers
How to call my contract's function using sendTransaction
This may be a very basic question, I don't know why but I am unable to find correct solution to how can I call my contract's method using sendTransaction. I have a transfer(address, uint256) function which I want to call using sendTransaction and…
Prashant Prabhakar Singh
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32
votes
4 answers
What is msg.value?
Can somebody explain what is the magic msg.value? I came across this code:
https://learnxinyminutes.com/docs/solidity/
/// @return The balance of the user after the deposit is made
function deposit() public payable returns (uint) {
// Use…
idoor
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32
votes
3 answers
Where is the state data stored?
This question was asked on Reddit a while ago:
Where is the state data actually stored though? On the hard drive of each node? Separate from or within the blockchain?
— Reddit: Basic Questions About the Ethereum EVM and State Storage
J-B
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32
votes
2 answers
Difference between keccak256 and sha3
I have been reviewing keccak256 implementation and sha3-256 that follows the FIPS standard. The sponge function is taking a while to set in, but I have noticed a difference in implementation :
I noticed web3.js uses crypto-js implementation of…
user2163865
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32
votes
4 answers
How to create a Dapp from scratch on Ethereum?
Let's say we have someone who knows about blockchain but who doesn't have any background in blockchain-based application.
That person wants to code an ethereum-based Dapp (decentralized application) as a proof of concept.
How to get started? What…
SajZ
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31
votes
11 answers
What public testnets (test networks) and faucets exist?
What public test-networks exist and what are their conditions?
What are the connection data?
How often (if so) are they reset?
Does a public faucet exist for this test network?
Does a block explorer exist for this test network?
How frequent/…
mKoeppelmann
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