Questions tagged [arrays]

Questions regarding the use of Arrays in solidity.

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103 views

What does State Trie save when pushing into array?

I'm interested/worried about the size of the State Trie over time Lets suppose I have a contract with two vars: uint myNumber; uint[] myArray; As far as I understand, If I change the value of "...
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1answer
19 views

Is it possible to return a table of values in solidity?

I am writing a code to return multiple values from two arrays simultaneously. I understand since I mentioned only one uint and one address as arguments in returns, the for loop is throwing an error. ...
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Solidity. Pushing a struct to an array. But that struct contains an array. Copying of type struct memory[] memory to storage not yet supported

Here is my code. I need to have a "checkpoint" object that stores some information including an array of "delegations" which is another object. struct delegation{ uint256 ...
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3answers
1k views

Unable to return address array in solidity

I have the following code for a simple gambling game. The code works fine except for getPlayers function pragma solidity >=0.4.22 <0.6.0; contract Lottery { address payable public manager; ...
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1answer
24 views

Storing nested array (2D array)

So I am making an ERC1155 token (for the batch mint pretty much). It is only ever going to mint NFT's (as you will see now now). I am trying to batch mint tokens and store an array for each one. So ...
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1answer
33 views

Adding element to mapping (solidity) is not working, even if the method is actually called in the transaction

I'm currently working (as a begineer) at a project involving ethereum blockchain and solidity. In my contract I have a mapping with addresses as key and the value of an array of a FileDetails ...
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0answers
21 views

invalid opcode while getting an element from a string of array

I am having some problems executing the final function of this contract (getmsg) this is the code: struct req{ uint yes; } struct fri{ uint yes; ...
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1answer
11 views

How to empty uint array after value is assigned?

Here is an uint array defined in smart contract: uint256[] public bidderItemID; And bidderItemID is assigned value in contract: bidderItemID = [1,2,3]; How can I empty bidderItemID after it is ...
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3answers
312 views

How do i add to a nested array within a struct

I am unable to add elements to a array within the struct struct D { string name; address key; } struct Aone { string aid; B[] blist; D[] dlist; } ...
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2answers
206 views

Arrays copy memory in Solidity

I have this simple code: function restart() public returns (uint256[] ) { uint256[] memory result = new uint256[](5); result[0] = 10; uint256[] memory result1 = new uint256[](5); ...
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1answer
371 views

solidity sorting array - LIFO / FIFO

I am adding to an bytes32[] array via push(). When I traverse the array with for (uint i = 0; i < array.length; i++), This is First in First Out (FIFO) sequence right? How can one perform a ...
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3answers
996 views

How to handle dynamic size string array in solidity?

I have a shop owner and a shop owner can have multiple products. I want to keep the products id in an array. Also, A public method can return all the product id list of a shop owner. I tried the ...
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1answer
19 views

Solidity: How to do 2D mapping?/Syntax Error

I am getting a syntax error. I am not sure if its a problem related to 2D mapping or 2D array. My code is given below: contract Stealing{ mapping (address => uint) balances; mapping (...
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3answers
4k views

Efficient approach to delete element from array in Solidity

For each user, I want to keep an array of holded assets (each asset has an ID). My solution up until now is : struct User { uint userId; uint[] assets; } For every asset the ...
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1answer
403 views

Setting values of an byte array dynamically

If I set the values of an array as follows, am I wrong? uint256 n = 0; bytes32[n] example; function getArraySize(uint256 arraySize) public returns(uint256 size) { size = arraySize; return size; }...
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3answers
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How to initialize an empty array inside a struct?

Is there a mistake in the way I initialize Bar b in the function foobar? contract Foo { struct Bar { address owner; uint[] x; } Bar[] public bars; function foobar(...
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1answer
13 views

Increase values in array

I am increasing the value at a particular index in Solidity but it is giving me bad instruction error. Can anyone tell me what I am missing here? Please check the sample contract for reference: pragma ...
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1answer
87 views

How do i loop through an array of structs? “TypeError: Integer constant expected.” Solidity

What i want my code to do Everytime the function is called the exampleValue of all users should be increased by 5 What the code actually does When i compile it in Remix i get this error message: ...
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1answer
18 views

array problem invalid opcode

new to ethereum. I'm tring to write smartcontracto to manage car rental. Can anyone explain me why the function to insert new car is not working (code below): function insertnewcar(string memory model,...
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2answers
187 views

Remove array specific value

In a array that the values are never repeated. Is there a function/library or something similar that you give the value to remove. And the function the empty space in the array?? function remove(uint ...
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1answer
23 views

Returning a dynamic array of structs

I'm trying to return a dynamic array of structs created on the fly from storage data, similar to how we return ViewModel from DB data in MVC. What is the best way of doing it in Solidity? Tried ...
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1answer
93 views

Ganache Storage

I am trying to push data to an address array within a struct array. There are no errors, however, when I check the storage of the array in my contract in Ganache, it remains empty. Is there something ...
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1answer
338 views

Standard work-around for using a Solidity constant array (which is not supported) in pure function?

I have an array in my contract like this and a pure method which uses it like this (simplified exmaple because my real exmaple is many more lines): uint[16] constant x = [10, 2, 6, 42, 19, 5, 4, 36, ...
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1answer
35 views

Declare an string array inside a int array in Solidity

I am using truffle and I am trying to pass during the deployment execution script a double array of prices inside my contract's constructor. ie In the migration file I have a 2 dimensional array. It's ...
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15 views

how to pass fix size array via interface in solidity 0.4.25

I used the following code interface test{ function testfunction(uint[20] memory P, uint[20] memory Q) external returns(uint,bool,uint); } It gives the error Location has to be calldata for external ...
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0answers
13 views

Arrays not showing up inside structures

I am creating a record of people and have created a structure struct asset{ uint assetId; string hash; address creatorAddress; uint cost; uint soldCount; } struct person{ uint ...
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24 views

How to retrieve all the values form the mapping?

Yield farming. Unaudited food token. Anon founder. Crazy APR%. Of course, if it is "too good to be true" it probably is... I would like to "don't trust, verify" and verify who is ...
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1answer
16 views

What is an efficient method to append a dynamic array to a dynamic array?

I'm looking for the most efficient method to append a dynamic array to an existing dynamic array. I know I could do: bytes4[] private _array1 = [1,2,3]; bytes4[] private _array2 = [4,5,6]; for( i =...
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1answer
24 views

Storing multiple values in one key mapping dynamically

I am making a blockchain project using solidity which requires storing various objectIDs corresponding to a personId. The person can add and remove objects and we cannot hard-code the number of ...
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1answer
59 views

How to encode arrays for solidity function calls

I want to understand how to encode the following arrays in Solidity. Dynamic Arrays For example, the following: function getDynamicUintArray() public pure returns (uint[] memory) { uint[] ...
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1answer
41 views

How can I distribute funds to present stakers efficiently?

I am building a smart contract which keep the token holder's eths for a while and give them rewards when they withdraw. The reward is given from the ethers collected by early withdraw of people. If ...
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0answers
14 views

Acess position in array vs Access key in mapping (uint IDs) - What's the efficient way?

I have a doubt about efficiency in solidity, when searching in lists of integer values, in mapping vs array. Array Imagine that I use the array position as element ID, and the content as the value, as ...
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23 views

How store memory array in storage

In this code, I want to send an array of bytes32 and store them in the struct but I get the error which is TypeError: Type string memory[8] memory is not implicitly convertible to expected type ...
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1answer
28 views

adding an struct instance into a dynamic array of struct objects

Consider this code. function getDoctorsList(uint[] memory _docIds) public view returns (doctor[] memory) { doctor[] memory _doctors; for(uint i = 0; i < _docIds.length; i++) { ...
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1answer
27 views

How to access the length of a public array?

Say I have the following contract: contract A { uint[1] public MyArray; constructor() public { MyArray[0] = 56; } } And I want to know the size of MyArray by looking it up ...
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1answer
29 views

Is it possible to call a public array from another contract?

Let's say there is a uint[] public MyArray declared in contract_A. Is there a possiblility to create an interface contract_A that would allow to read the values in MyArray from another contract, or ...
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1answer
61 views

Deleting an array in storage (>= 0.6.0)

I need to add elements to a resizable myArray and then delete the myArray. I don't know what the length of myArray will be before the loop, and it's not possible to resize a memory array; that leaves ...
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0answers
12 views

EthersJS returns array double wrapped i.e [ [“0x838383…”, “0x3BC2…”, ] ]

I have a method that is supposed to return an array of deployed contract addresses, it works albeit the value that is returned client side is wrapped with an extra set of brackets and also when ...
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0answers
28 views

Checking if an item present in an array in Solidity

I want to check whether a specific item is included in an array or not. For example, consider the following array. uint[] a = [1, 2, 3, 4] Is there any way that I can get true if I have given 4, and ...
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1answer
11 views

push to a temporary array within a function

I come from nodejs and this seems odd to me.. can't seem to push anything to a temporary array. function get_unconfirmed() public view returns (address[] memory, uint[] memory, uint[] memory) { ...
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2answers
524 views

Solidity & truffle: get elements from strings array

i'm glad to follow this forum, it is very helpful. I'm using truffle to develop contracts and i just found that dynamic arrays are not yet suported, for that reason i was using string arrays with a ...
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0answers
27 views

join an array of strings and map, filter, reduce functions in solidity

I want to concatenate an array of strings into a single string using solidity, just like the array join function in javascript and python. Also I want to do map/filter/reduce functions in an array. Is ...
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1answer
50 views

Can you have an array of mappings? The mappings have an address key and a struct value

Can you have an array of mappings? I want to have mappings with addresses as keys and structs as the value. I want to store these addresses in an array and iterate through them. so far it looks like ...
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1answer
455 views

How to Serialize/Deserialize array of bytes?

I'm writing a smart contract and inevitably need to have arrays of bytes as input and output of functions. In remix arrays work just fine but with web3j and web3js there are several issues with arrays ...
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2answers
323 views

Solidity 0.4.26 check if element already exists in array

How do I make it so this only adds an identifier to the dataArray if it doesn't exist already? pragma experimental ABIEncoderV2; contract structWithMapping{ struct Data{ string[] user; ...
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1answer
82 views

How to return values from dynamic array push function?

How to fetch value from dynamic array push function? Below is the code of pushing function, but how will I fetching that array values? contract PushStruct { struct MyStruct { uint field1; ...
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4answers
911 views

loop to find the highest value in an array

I have made a struct which has an address called playersAddress and a uint called numbers. I then have a fixed sized array which has in it the playersAddress and the numbers. When someone calls ...
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1answer
127 views

Error when trying to view return values

I've written the following contract contract Catalog{ address[] internal array; function pushItem(address _el) external{ array.push(_el); } function getArray() external ...
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1answer
300 views

Member “push” not found or not visible after argument-dependent lookup in address[] storage ref

I am failing to use the push method against a dynamic array declared as a state variable. How can I do this? I declare a dynamic array of addresses as a state variable like below: contract Sample { ...
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3answers
6k 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....

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