Struct

Struct types are used to represent a record. Suppose you want to keep track of your books in a library, you might want to track the following attributes about each book

Title
Author
Subject
Book ID

Defining a Struct

To define a Struct, you must use the struct keyword.
The struct keyword defines a new data type, with more than one member.

The format of the struct statement is as follows

struct struct_name { 
   type1 type_name_1;
   type2 type_name_2;
   type3 type_name_3;
}

Example:

struct Book { 
   string title;
   string author;
   uint book_id;
}

Accessing a Struct and its variable

We use the member access operator (.)
The member access operator is coded as a period between the structure variable name and the structure member that we wish to access.
You would use the struct to define variables of structure type.

The following example shows how to use a structure in a program.

Example:-1

pragma solidity ^0.5.0;

contract test {
   struct Book { 
      string title;
      string author;
      uint book_id;
   }
   Book book;

   function setBook() public {
      book = Book('Learn Java', 'TP', 1);
   }
   function getBookId() public view returns (uint) {
      return book.book_id;
   }
}

Example:-2

// SPDX-License-Identifier: GPL-3.0
 
pragma solidity >=0.7.0 <0.9.0;
 
contract LearnStruct {
    struct Movie {
        string director;
        string title;
        uint256 movie_id;
    }
    // struct acts as a new datatype  and we can assign it to variables like so
    Movie movie;
 
    function setMovie() public {
        // assignment is done like so
        movie = Movie("Blade runner", "Ridley scott", 1);
    }
 
    function getMovie() public view returns (Movie memory) {
        return movie;
    }
 
    function getMovieId() public view returns (uint256) {
        return movie.movie_id;
    }
}

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Struct

Defining a Struct

Accessing a Struct and its variable