I created a function that stores data. But this function cannot receive data. I tried it without calldata, with memory but all this ways didn't work. Thanks for the help.
pragma solidity >=0.7.0 <0.9.0;
contract Test {
struct Messanges{
string message;
address sender;
}
Messanges[] public chatverlauf;
address a = 0x5B38Da6a701c568545dCfcB03FcB875f56beddC4;
function add(string calldata _message, address calldata _sender) public{
//chatverlauf.push(Messanges(_message, _sender));
Messanges memory newMessage;
newMessage.message = _message;
newMessage.sender = _sender;
chatverlauf.push(newMessage);
}
i lookt up in this but it didn't workt for me
https://ethereum.stackexchange.com/questions/83602/data-location-can-only-be-specified-for-array-struct-or-mapping-types-but-mem/83603
written with remix
the compiler version is 0.8.10
change
function add(string calldata _message, address calldata _sender) public
to
function add(string _message, address _sender) public
In Solidity 0.8.0 only array , struct and mapping type can specific data location.
Related
I tried to create a factory for ERC-20 token in rinkeby network taking reference from bscscan-BEP20Factory. But I am not able to verify the contract. The link for my contract is here.
My Contract code is:
pragma solidity 0.8.4;
import "#openzeppelin/contracts/proxy/transparent/TransparentUpgradeableProxy.sol";
import "./interfaces/IProxyInitialize.sol";
contract ERC20TokenFactory{
address public logicImplement;
event TokenCreated(address indexed token);
constructor(address _logicImplement) {
logicImplement = _logicImplement;
}
function createBEP20Token(string calldata name, string calldata symbol, uint8 decimals, uint256 amount, bool mintable, address erc20Owner, address proxyAdmin) external returns (address) {
TransparentUpgradeableProxy proxyToken = new TransparentUpgradeableProxy(logicImplement, proxyAdmin, "");
IProxyInitialize token = IProxyInitialize(address(proxyToken));
token.initialize(name, symbol, decimals, amount, mintable, erc20Owner);
emit TokenCreated(address(token));
return address(token);
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
interface IProxyInitialize {
function initialize(string calldata name, string calldata symbol, uint8 decimals, uint256 amount, bool mintable, address owner) external;
}
Following is the error:
enter image description here
The top SO or ETH Stack Exchange answers don't seem to apply to my case (I could be wrong of course)
I'm getting the error describer in the title in this file:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "./ERC721Metadata.sol";
import "./ERC721.sol";
contract ERC721Connector is ERC721Metadata, ERC721 {
// ^^^^^^^ (Definition of base has to precede definition of derived contract)
constructor(string memory name, string memory symbol) ERC721Metadata(name, symbol) {}
}
Here's what ERC721Metadadata looks like:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
contract ERC721Metadata {
string private _name;
string private _symbol;
constructor(string memory named, string memory symbolified) {
_name = named;
_symbol = symbolified;
}
function name() external view returns (string memory) {
return _name;
}
function symbol() external view returns (string memory) {
return _symbol;
}
}
And here is what ERC721 looks like:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "./ERC721Metadata.sol";
import "./ERC721Connector.sol";
contract ERC721 {
event Transfer(
address indexed from,
address indexed to,
uint256 indexed tokenId
);
mapping(uint256 => address) private _tokenOwner;
mapping(address => uint256) private _OwnedTokensCount;
function _exists(uint256 tokenId) internal view returns (bool) {
address owner = _tokenOwner[tokenId];
return owner != address(0);
}
function _mint(address to, uint256 tokenId) internal {
require(to != address(0), "ERC721: minting to the zero address");
require(
!_exists(tokenId),
"ERC721: minting a token that already exists (been minted)"
);
_tokenOwner[tokenId] = to;
_OwnedTokensCount[to] += 1;
emit Transfer(address(0), to, tokenId);
}
}
Do you need to import ERC721Connector contract in your ERC721 contract? If not, you can remove
import "./ERC721Connector.sol"; // line 4, ERC721.sol
from your file and it should work fine. Your imports are causing the issue,
ERC721Connector tries to import ERC721, but ERC721 also needs ERC721Connector so the compiler says
Definition of base has to precede definition of derived contract
Because the base contract doesn't precede the defined contract.
In the following claimPayment function that is used to claim a payment made earlier to this contract, the line bytes32 message = prefixed(keccak256(abi.encodePacked(msg.sender, amount, nonce, this))); has this as part of the signed message. This makes me wonder what is this and what the type of this is. If I'm returning this in a function, what type is used for it? Thanks.
function claimPayment(uint256 amount, uint256 nonce, bytes memory signature) public {
require(!usedNonces[nonce]);
usedNonces[nonce] = true;
// this recreates the message that was signed on the client
bytes32 message = prefixed(keccak256(abi.encodePacked(msg.sender, amount, nonce, this)));
require(recoverSigner(message, signature) == owner);
payable(msg.sender).transfer(amount);
}
this is a pointer to the current class instance, as in many other programming languages. You can for example point to public methods:
pragma solidity ^0.8.0;
contract MyContract {
function foo() external {
this.bar();
}
function bar() public {
}
}
When this is typecasted, it takes a form of the address, where the current instance is deployed.
pragma solidity ^0.8.0;
contract MyContract {
function foo() external view returns (bytes memory) {
return abi.encodePacked(this);
}
function bar() external view returns (address) {
return address(this);
}
}
How to use TRON address in solidity.
I am unable to use deployed smart contract by TRON address.
How its possible.
Please help.
// SPDX-License-Identifier: MIT
pragma solidity >=0.4.22 <0.8.0;
abstract contract TRC20 {
function decimals() public virtual returns (uint8);
}
contract Matrix {
function greet() public payable returns (uint8) {
TRC20 t = TRC20(TKssrn5v8ephdmJbh7UYaUeoR4L1d4ZXds);
return t.decimals();
}
}
TKssrn5v8ephdmJbh7UYaUeoR4L1d4ZXds address is in base58 format, you'll need to convert it into hex format.
Using your example, you can change greet function to take an address argument.
function greet(address _address) public payable returns (uint8) {
TRC20 t = TRC20(_address);
...
You can then convert the address from base58 format to hex format using tronWeb's to hex function.
tronweb.address.toHex('TKssrn5v8ephdmJbh7UYaUeoR4L1d4ZXds')
I am creating a smart contract in solidity ^0.5.1 in which I get the following error:
data location must be a memory for the return parameter in the function, but none was given.
In the below function I am getting error.
function getCitizen()public returns(address[]){
return citizenArray;
}
The smart contract that I have tried so far.
pragma solidity ^0.5.1;
contract Citizen{
struct Citizens{
uint age;
string fName;
string lName;
}
mapping(address => Citizens) citizenMap;
address [] citizenArray;
function setCitizen(address _address,uint _age,string memory _fName,string memory _lName) public{
//creating the object of the structure in solidity
Citizens storage citizen=citizenMap[_address];
citizen.age=_age;
citizen.fName=_fName;
citizen.lName=_lName;
citizenArray.push(_address) -1;
}
function getCitizen(address _address) public pure returns(uint,string memory ,string memory ){
return(citizenMap[_address].age,citizenMap[_address].fName,citizenMap[_address].lName);
}
function getCitizenAddress()public returns(address[]){
return citizenArray;
}
}
How can I return the array of addresses?
It make sense, as you are returning the storage array of address you cannot return it as it is, because it will try to return the actual address of citizenArray in the contract storage. You can send the array by making it in memory. Like this.
function getCitizenAddress()public view returns( address [] memory){
return citizenArray;
}
Once you put it as memory, you will get the warning for this which will state that as you are not changing any state in the function, you should mark it view, I already did that in the above code.
Lastly, when you resolved this error, you will get another error in this function:
function getCitizen(address _address) public pure returns(uint,string memory ,string memory ){
return(citizenMap[_address].age,citizenMap[_address].fName,citizenMap[_address].lName);
}
This error is because you mark this function as pure. There is a little but very important difference between pure and view.
view means you cannot change the state of the contract in that function.
pure means you cannot change the state in the function and not even can read the state or storage variables.
In the above function of getCitizen you are actually doing read operations in your return statement. You can fix this by just putting view instead of pure. Like So:
function getCitizen(address _address) public view returns(uint,string memory ,string memory ){
return(citizenMap[_address].age,citizenMap[_address].fName,citizenMap[_address].lName);
}
I hope it will resolve all your issues. Thanks
// SPDX-License-Identifier: MIT
// Version
pragma solidity >=0.8.0 < 0.9.0;
contract EstructuraDeDatos {
struct Customer {
string nameCustomer;
string idCustomer;
string emailCustomer;
}
mapping(address => Customer) public myClientes;
address[] public listClientes;
function registrationApp(string memory _name, string memory _id, string memory _email) public {
Customer memory customer = Customer(_name, _id, _email);
myClientes[msg.sender] = customer;
listClientes.push(msg.sender);
}
function retornarArrat() public view returns (address[] memory) {
return listClientes;
}
}
// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.7.0 <0.9.0;
contract Citizen {
struct Citizens {
uint age;
string fName;
string lName;
}
mapping(address => Citizens) citizenMap;
address [] citizenArray;
function setCitizen(address _address,uint _age,string memory _fName,string memory _lName) public {
// Citizens storage citizen=citizenMap[_address];
//creating the object of the structure in solidity
Citizens storage citizen;
citizen = citizenMap[_address];
citizen.age=_age;
citizen.fName=_fName;
citizen.lName=_lName;
citizenArray.push(_address);
}
function getCitizen(address _address) public view returns(uint,string memory ,string memory) {
return (citizenMap[_address].age,citizenMap[_address].fName,citizenMap[_address].lName);
}
// function getCitizenAddress()public returns(address[]) {
// return citizenArray;
// }
}
// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.7.0 <0.9.0;
contract Citizen{
struct Citizens{
uint age;
string fName;
string lName;
}
mapping(address => Citizens) citizenMap;
address [] citizenArray;
function setCitizen(address _address,uint _age,string memory _fName,string memory _lName) public{
// Citizens storage citizen=citizenMap[_address];
//creating the object of the structure in solidity
Citizens storage citizen;
citizen = citizenMap[_address];
citizen.age=_age;
citizen.fName=_fName;
citizen.lName=_lName;
citizenArray.push(_address);
}
function getCitizen(address _address) public view returns(uint,string memory ,string memory ){
return(citizenMap[_address].age,citizenMap[_address].fName,citizenMap[_address].lName);
}
function getCitizenAddress()public view returns(address[] memory){
return citizenArray;
}
}