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Lesson 6:
Arrays
Introduction to Solidity Arrays
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Arrays
Arrays can have a compile-time fixed size, or they can have a dynamic size.
The type of an array of fixed size k and element type T is written as T[k], and an array of dynamic size as T[].
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;
contract ArrayExample {
// An array of fixed size 3 and element type uint
uint[3] public fixedArray = [1, 2, 3];
// An array of dynamic size and element type uint
uint[] public dynamicArray;It is possible to mark state variable arrays public and have Solidity create a getter(which you will learn later in the challenges). The numeric index becomes a required parameter for the getter.
More array examples:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;
contract Array {
// Several ways to initialize an array
uint256[] public arr;
uint256[] public arr2 = [1, 2, 3];
// Fixed sized array, all elements initialize to 0
uint256[10] public myFixedSizeArr;
function get(uint256 i) public view returns (uint256) {
return arr[i];
}
// Solidity can return the entire array.
// But this function should be avoided for
// arrays that can grow indefinitely in length.
function getArr() public view returns (uint256[] memory) {
return arr;
}
function push(uint256 i) public {
// Append to array
// This will increase the array length by 1.
arr.push(i);
}
function pop() public {
// Remove last element from array
// This will decrease the array length by 1
arr.pop();
}
function getLength() public view returns (uint256) {
return arr.length;
}
function remove(uint256 index) public {
// Delete does not change the array length.
// It resets the value at index to it's default value,
// in this case 0
delete arr[index];
}
function examples() external pure {
// create array in memory, only fixed size can be created
uint256[] memory a = new uint256[](5);
}
}