ArraysAndMapppings.sol

pragma solidity ^0.6.0;

contract MyContract {
    // Arrays
    uint[] public uintArray = [1,2,3];
    string[] public stringArray = ['apple', 'banana', 'carrot'];
    string[] public values;
    uint[][] public array2D = [ [1,2,3], [4,5,6] ];

   
   function addValue(string memory _value) public {
        values.push(_value);
   }
   
    function valueCount() public view returns(uint) {
        return values.length;
    }  

    // Mappings
    mapping(uint => string) public names;
    mapping(uint => Book) public books;
    mapping(address => mapping(uint => Book)) public myBooks;

    struct Book {
        string title;
        string Author;
    }

    constructor() public {
        names[1] = "Adam";
        names[2] = "Bruce";
        names[3] = "Carl";
    }
    
    function addBook(uint _index, string memory _title, string memory _author) public {
        books[_index] = Book(_title, _author);
    }

    function addMyBook(uint _index, string memory _title, string memory _author) public {
        myBooks[msg.sender][_index] = Book(_title, _author);
    }
}