I am trying the following code but got that error.
If I add memory inside functions params I got new error:
TypeError: Data location can only be specified for array, struct or mapping types, but "memory" was given.
pragma solidity 0.8.7;
mapping (string => uint) wallet;
function saveWalletData(uint _qty , string _name) public{
wallet[_name] = _qty;
}
function consultarWallet(string _name) public view returns(uint){
return wallet[_name];
}
string is a reference type in Solidity. For all reference types, you need to specify their data location (docs).
In this case, you can use calldata for both, because you're not modifying value of the _name variable.
function saveWalletData(uint _qty , string calldata _name) public{
wallet[_name] = _qty;
}
function consultarWallet(string calldata _name) public view returns(uint){
return wallet[_name];
}
If you wanted to modify the value in memory, you'd need to use memory.
solidity newbie here. when I try to read the value of the people array. I'm getting an error:
call to SimpleStorage.people errored: Error encoding arguments: Error:
invalid BigNumber string (argument="value" value=""
code=INVALID_ARGUMENT version=bignumber/5.4.2)
my compiler version is 0.6.6. not sure what's wrong? any suggestions?
// SPD-License_Identifier: MIT
pragma solidity ^0.6.0;
contract SimpleStorage {
uint256 favNum;
struct People {
uint256 favNum;
string name;
}
People[] public people;
function store(uint256 _favNum) public {
favNum = _favNum;
}
function retrieve() public view returns(uint256) {
return favNum;
}
function addPerson(string memory _name, uint256 _favNum) public {
people.push(People(_favNum, _name));
}
}
The error happens when you're trying to call the people() function (from Remix IDE) without passing any value.
Since the People[] public people is a public property, it autogenerates a getter function during compilation. But because it's an array, the getter function requires an uint256 param specifying the index of the array that you want to retrieve.
When you pass an empty string, Remix tries to encode it to the BigNumber instance, but this fails. Only when you pass an (existing) index of the array, it works correctly:
If you want to get the whole array in one call, you need to create a separate getter function:
function getAllPeople() public view returns (People[] memory) {
return people;
}
You must click on the small arrow to the right of the deploy button, then the fields will be displayed so that you can complete the data that the contract must receive.
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;
}
}
when trying to set up an array of structs i get an error that says "Undeclared identifier. Did you mean "Candidate" or "candidate"?"
Ive tried to create an empty array by writing
uint[] memory candidate;
and
bytes[] memory candidate
above the function in which i'm getting errors to instantiate it. However, this doesn't work either and gives errors. It does not compile.
pragma solidity 0.5.0;
contract Election {
string public candidate;
struct Candidate {
uint id;
string name;
uint voteCount;
}
mapping(uint => Candidate) candidate;
uint public candidatesCount;
function createCandidate(string storage name ) private {
candidatesCount ++;
candidates[candidatesCount] = Candidate(candidatesCount, name, 0);
}
function addCandidates () public {
createCandidate("Candidate1");
createCandidate("Candidate2");
}
}
change
mapping(uint => Candidate) candidate;
to
mapping(uint => Candidate) candidates;
and
function createCandidate(string storage name ) private
to
function createCandidate(string memory name ) private
I have a contract with the following data structures:
struct Answer
{
bytes32 name; // short name (up to 32 bytes)
uint voteCount; // number of accumulated votes
}
struct Question
{
bytes32 name; // short name (up to 32 bytes);
Answer[] answers;
}
Question[] public questions;
How can I fill the arrays?
The following lines are not functional:
function addQuestion(bytes32 _name, bytes32[] _answers) onlyOwner { // perhabs it should be possible that others as the owner can add
Answer[] memory answersLocal = new Answer[](_answers.length);
//Question memory question = Question(_name);
for (uint i = 0; i < _answers.length; i++) {
answersLocal[i] = Answer({
name: _answers[i],
voteCount: 0
});
}
questions.push(Question({
name: _name,
answers: answersLocal
}));
}
I get here the error:
Copying of type struct Roadshow.Answer memory[] memory to storage not yet supported.
if you are trying to access contract via web3 or something bridge like this.
the bridge still not support array of arrays, but solidity supports!
i guess if the error was in solidity you will see a different type of error.
Hope this helps.
Use push() method instead of Solidity assigning.