The array is a data structure to store multiple variable values under a single name.

For example, If we want to store three numbers,

Declare and assign three variable values with same int type,Example is number1=0,number2=1,number3=1.

With arrays, we can represent a single variable to store all values. Each value of an array can be accessed using an index that starts from zero to array.length-1.

Array is one of the reference types defined in a solidity programming language.

Arrays are of two types

  • Fixed array: Array created with a fixed size of elements during declaration.
  • Dynamic array: Array created with dynamic size and no fixed size size

How to declare an array in a solidity?

Variables declared of a string with below syntax.

type[size]  arrayvariablename =initialization;

type is a data type of an array of data i.e value or reference types. size is several elements to store for arrays. size is optional for the dynamic array. arrayvariablename is a valid identifier and valid names are alphanumeric which starting must be a letter. Reserved words not used with value. initialization: initialize the data for an array

Fixed Array in Solidity

A string array is created with a fixed size of 5 elements.

string[5] stringArray; 

Dynamic Array in Solidity

dynamic array is dynamically grown array size during the execution of code. No fixed size.

string[] numbers;

How to initialize a static string array in solidity?

Arrays can be declared as global in contract or inside the function.

Array variable created with assigning the values using square brackets

pragma solidity ^0.8.4;

contract StaticArrayTest {
    string[3] numbers = ["one", "two", "three"];
    
    function getNumbers() external {
        string[3] memory mynumbers = ["one", "two", "three"];
    }
}

How to return arrays from functions

By default, It does not support returning an array from a function.

ABIEncoderV2 experimental needs to be used in a contract.

pragma solidity ^0.5.2;
pragma experimental ABIEncoderV2;

contract Test {

    string[] array;

    function push(string calldata _text) external {
        array.push(_text);
    }

    function get() external view returns(string[] memory) {
        return array;
    }
}

Operators and methods

length: length of an array push: adds an element to a dynamic array. It adds an element to the last position of an array. pop: removes an element from the dynamic array. It deletes an element from the last element of an array.