All Questions
253 questions
54
votes
8
answers
32k
views
How to quickly test a Solidity function?
There are snippets and functions of Solidity code provided on this Ethereum Stack Exchange and other sites. What are ways to quickly test them, possibly debug a little, and play around?
eth♦
- 86.5k
45
votes
3
answers
15k
views
What is the difference between transaction cost and execution cost in remix?
What is the difference between transaction cost and execution cost as seen after contract instantiation in remix?
I don't think it matters, but here is my contract:
contract DepositCounter {
...
- 3,610
4
votes
2
answers
4k
views
Remix Warning - No visibility specified, Violate Checks-Effects-Interaction pattern, Function state mutability can be restricted to pure - Can ignore?
Two months ago, I wrote a smart contract with Remix.ethereum.org. Line 1 of my code has:
pragma solidity ^0.4.11;
It compiled fine with no errors and nor warnings. I tested every function in ...
- 307
75
votes
7
answers
134k
views
How do you get a json file (ABI) from a known contract address?
I want to watch a Solidity contract using the Mist browser. I know how to do that and it needs the address and the json. I have the address, but I don't have the json. I do have the source code.
Can ...
- 10k
14
votes
5
answers
6k
views
How to Compile and Deploy a Smart Contract without running a full node?
I'm new to solidity and smart contract programming. I have already made and deploy smart contracts successfully, but always using Mist.
Now I'm not able to do so, because I can't complete a node ...
28
votes
2
answers
29k
views
How to pass arbitrary bytes to a function in Remix (2017)
According to this question I could write a simple contract like:
contract SimpleStorage {
bytes input;
function setInput(bytes enterBytes){
input = enterBytes;
}
}
Using "0x1234" as a ...
- 599
23
votes
5
answers
29k
views
How to estimate gas at contract creation/deployment to private ethereum blockchain
What I have done
a) When I use web3.eth.estimateGas to estimate the cost of a contract creation constructor with no parameters, the estimate is correct.
b) If the contract is already deployed then ...
- 871
12
votes
1
answer
8k
views
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 ...
- 369
12
votes
5
answers
18k
views
Invalid JSON RPC response: "" In Browser-Solidity
I'd like to connect private geth node from browser-solidity, however it returned the error Invalid JSON RPC response: "".
Please check the following picture for details.
Could you tell me how to ...
- 2,357
9
votes
3
answers
7k
views
Convert an eth key to a geth key
I need to convert my eth key to a geth key.
eth put the key in %appdata%\roaming\Web3\keys, and I see it as a .json file. If I move that to the %appdata%\roaming\Ethereum\keystore directory, geth ...
- 93
4
votes
1
answer
2k
views
Transfer only available for objects of type "address payable", not "address"
I am reading the book Mastering Blockchain Programming With Solidity by Jitendra Chittoda published by Packt Publishing. On page 129 it has a sample contract to deploy using the Remix IDE and MetaMask....
- 143
14
votes
2
answers
9k
views
Using ".value(...)" is deprecated. Use "{value: ...}" instead
This works fine in Remix but when trying to work in VSCode (for compiling purposes; DApp course, trying to build .json through compile.js ) it throws the error
Using ".value(....
- 143
9
votes
1
answer
2k
views
What is the cryptic part at the end of a solidity contract bytecode?
Given the following contract:
pragma solidity ^0.4.11;
contract Simple {
bytes32 public v;
function set(bytes32 _v) {
v = _v;
}
}
When disassembling, neither remix, solc or evm ...
- 685
10
votes
2
answers
27k
views
How can i transfer ERC20 tokens from a contract to an user account?
I have deployed an ERC20 token (contract A) and the tokens are being used for a service in my other contract (Contract B). I can easily transfer tokens from an user owned account(EOA) to Contract B ...
- 123
8
votes
3
answers
15k
views
Getting infinite gas estimates for simple functions
I am testing out solidity in remix ide using simple contracts. This is the contract that I wrote:
contract mortal {
address owner;
function mortal() {
owner = msg.sender;
}
function kill(){
...
- 183
8
votes
1
answer
20k
views
How to load contract from address- remix?
Hi I just found that remix added "Load contract from address" option. So I tried to load contract from address "0x67601d7a7cbbD77368785122c508503f168B1dAa" . You can see this contract is in function ...
- 417
7
votes
1
answer
10k
views
ETH sent to ETC address
I accidentally sent ALL my ETH on ETC address :(
6 months of mining gone :(
I sent from one exchange to fresh address on another exchange, but on ETC ...
Is there ANY way to track those coins?
I'm ...
6
votes
2
answers
11k
views
calling one contract to another contract method
I want to call the method getdata() and retrieve the returns value to use in another contract. But the call only returns bool on success or failure.
How do I get the return value from ...
- 2,249
4
votes
1
answer
649
views
Can geth and eth share the same accounts and blockchain?
It appears when I have multiple ethereum clients installed, that they all have their own data, accounts and even their own copy of the blockchain.
Is it possible to share accounts and the blockchain ...
- 33k
2
votes
1
answer
3k
views
Airdropping ERC20 Tokens to multiple addresses in a single transaction
done , wrong question.
better to use this
contract ERC20 {
function transfer(address _recipient, uint256 _value) public returns (bool success);
}
contract Airdrop {
function drop(ERC20 token, ...
user19060
2
votes
1
answer
3k
views
Got scammed using bad code to create front running bot [duplicate]
I got scammed by bad code on a front running bot. I used the code in Remix, deployed it, and then sent money to it. (Put another way, I don't code, had no idea what I was doing, but decided to try it ...
- 21
0
votes
2
answers
448
views
Why transfer funds breaks contract?
My deployed contract called successfully only by "function invocation" through web3 or Remix. But it always failed when I sending funds to the contract.
I thought that only requirement that contract ...
- 1,277
34
votes
3
answers
41k
views
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 ...
- 835
33
votes
3
answers
31k
views
How does Mapping in solidity work?
I went through the Crowdfunding example in solidity where i encountered the following:
contract Crowdfunding {
struct CampaignData {
address recipient;
uint contributed;
uint goal;
...
- 1,303
26
votes
4
answers
28k
views
How to fill dynamic in-memory array
For some reason solidity doesn't allow to push values into memory array
Member "push" is not available in bytes32[] memory outside of
storage.
Here is sample contract code:
pragma solidity ^0.4....
- 491
18
votes
3
answers
10k
views
Etherscan: How can I verify a contract with multiple imports deployed with Truffle?
When I deploy a contract with Truffle that has an import statement, and try to verify it on etherscan, my understanding is that I need to paste in the contents of the imported file.
I get an error on ...
- 1,535
17
votes
4
answers
26k
views
What is the maximum value an int and uint can store
I need to understand a couple of things:
What is the maximum value an int and uint can store?
Are the maximum values stored in int and uint the same?
- 813
7
votes
1
answer
3k
views
How can I deploy a contract with reference to a library contract without using a graphical user interface like Browser Solidity?
I am using Solidity Browser to deploy a contract due to from Library contract method failing #2831 issue. On this following answer https://ethereum.stackexchange.com/a/9181/4575 I have guided to use ...
- 8,404
4
votes
1
answer
5k
views
How can I import geth accounts into eth?
I had two accounts under ~/.ethereum/keystore when I used geth a while ago.
I got a new PC, recompiled only the C++ version and I can't see my two accounts in eth.
web3.admin.eth.allAccounts() ...
- 4,640
2
votes
3
answers
5k
views
Issue with New version of Metamask: Remix cannot detect the Metamask address
I have just installed Metamask version: 6.3.1
Now in Remix, the address of my account in metamask is not detected. The account box in remix remains always blank now (see picture below).
Note that I ...
- 257
1
vote
1
answer
8k
views
I sent My ETC to my ETH address
I've sent a mistake ETC from ETH address from poloniex.
How do i do now.
This is my transaction (this is a fresh address)
http://gastracker.io/tx/...
- 13
1
vote
1
answer
1k
views
Remix: Invalid parameters: must provide an Ethereum address
I have a contract ready for deployment on REMIX and also have 3 Rinkeby Metamask accounts. Only 1 of these accounts is able to deploy the contract for some reason. When i try the other 2 accounts i ...
- 111
28
votes
7
answers
43k
views
TypeError: Data location must be "memory" for parameter in function, but none was given
I have created the contract below using the online IDE Remix. the smart contract was fine until late last night when i got the following error for all functions(targeting the string data types ...
- 391
26
votes
6
answers
38k
views
What is address(this) in solidity?
As per my understanding contract`s own address is the address which we assign to owner of contract using msg.sender.
But I saw this question on SE where it was described that a contract can access its ...
- 885
13
votes
3
answers
27k
views
How to get the contract ABI in new Remix IDE?
Waked up today just to find out the remix browser interface changed to this
what happened !!? I cannot find the contract details to get the json interface anymore.
- 175
13
votes
1
answer
5k
views
Gas consumption of a view public function
In my contract I have a view public function that returns an array of bytes32 elements. In remix it produces a warning saying it might run out of block gas limit if I use this function.
As I had read ...
- 199
9
votes
1
answer
15k
views
Debugging Ethereum Contract by printing the values
Is there a way that I can print the intermediate result on a console or some log file in order to debug my contract?
- 145
8
votes
3
answers
5k
views
Returning structs in new version in Solidity
I have been reading about Solidity release version 0.4.17.
https://github.com/ethereum/solidity/releases
One of the following statements was really interesting:
We also worked further on the new ...
- 83
7
votes
2
answers
14k
views
TypeError: This type is only supported in the new experimental ABI encoder
I am practicing my Solidity skills and while I did expect to get an error, I did not expect this error
TypeError: This type is only supported in the new experimental ABI
encoder. Use "pragma ...
- 501
6
votes
3
answers
3k
views
A problem with filters and events (web3j/TestRPC). SOS! ;)
Help me, please, with this little simple task! I cannot solve this problem for several days. SOS! ;)
I'm trying to write a program for filtering events via web3j. I copied to start (for the test) from ...
- 71
6
votes
2
answers
4k
views
Solidity function gas requirement is infinite
struct userData{
uint val;
bool isvalue;
string name;
}
mapping(uint => address) internal users;
mapping(address => userData) internal bidirectionalUsers;
function addMember(...
- 417
6
votes
2
answers
10k
views
How to install eth on debian? (symbol lookup error)
I installed from the ubuntu ppa and got this error.
➜ ~ eth
eth: symbol lookup error: eth: undefined symbol: _ZN3dev3eth14EthashGPUMiner14s_numInstancesE
What can I do / check?
I'm on debian ...
- 4,640
6
votes
1
answer
674
views
Compiler Issue or Improper State Variable declaration?
After seeing some unexpected compiler results, I've reduced the issue to this tiny example:
The following compiles under 0.4.10 in Remix:
contract StorageMapping {
struct S {
mapping(...
- 55.6k
6
votes
1
answer
371
views
Public variable getter shows as transaction in Remix
As of Solidity 0.6.0+ compiler, my remix shows getter functions, built by public variables, as transactions and, therefore, do not return the value. I searched the solidity 0.6.0 breaking changes but ...
- 1,423
6
votes
2
answers
8k
views
No matching declaration found after argument-dependent lookup
Currently I'm trying to find a solution for this problem TypeError: Member "toTimestamp" is not available in contract DateTime outside of storage , and I decided to take another approach. I'...
- 1,730
5
votes
1
answer
13k
views
The ERC-20 Token Transfer might have Failed (ErrCode: unable to locate corresponding Transfer event log), check with sender
EtherScan.io is showing error: The ERC-20 Token Transfer might have Failed (ErrCode: unable to locate corresponding Transfer event log), check with sender.
Transactions are successful but users are ...
- 51
5
votes
1
answer
4k
views
How to deploy contract into local running node using solidity browser?
I am running a local ethereum node and I did unlock an account.
Now I want to use the solidity browser to deploy that contract, but when I switch to the web3 provider deploy option and I press the ...
- 782
5
votes
5
answers
5k
views
How can I use testrpc as the environment in Remix?
I've installed ethereumjs-testrpc and I'm running it with testrpc in my terminal, which I'm pretty sure is working because it outputs Listening on localhost:8545 after listing all the test accounts' ...
- 157
5
votes
1
answer
4k
views
Remix IDE: What is the purpose of Calldata and Transact Tab
I am trying to execute the following code on Remix IDE.
pragma solidity ^0.5.4;
contract GuessTheNumberChallenge {
constructor() public payable {
require(msg.value == 1 ether);
}
...
- 1,416
5
votes
3
answers
4k
views
How to execute Smart contracts on a private Blockchain network
I have created a private Blockchain network on my Windows system with one node. I have created accounts and was able to transfer ethers across them. Now I want to deploy smart contracts on this ...
- 1,303