C# Structures Tutorial

1- What is Struct?

In C#, Struct (structure) is a special type of value, it creates a variable, to store multiple values, but the values are related to each other.
For example, information about an employee include:
  • Employee number
  • Employee name
  • Position
You can create 3 variables to store the information above of employee. However you can create a Struct to store all three information on in a single variable.
C # uses   struct keyword to declare a Struct.
Employee.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CSharpStructureTutorial
{
    struct Employee
    {

        public string empNumber;
        public string empName;
        public string position;

        public Employee(string empNumber, string empName, string position)
        {
            this.empNumber = empNumber;
            this.empName = empName;
            this.position = position;
        }
    }

}
For example, use Struct:
EmployeeTest.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CSharpStructureTutorial
{
    class EmployeeTest
    {

        public static void Main(string[] args)
        {
            Employee john = new Employee("E01","John", "CLERK");

            Console.WriteLine("Emp Number: " + john.empNumber);
            Console.WriteLine("Emp Name: " + john.empName);
            Console.WriteLine("Emp Position: " + john.position);

            Console.Read();
        }
    }

}
Running the example:

2- Struct vs Class

Struct is commonly used to create an object to store the value, while the class is using  more diversely.
  1. Struct does not allow inherit, it can not expand from a certain class or a struct.
  2. Struct does not allow implement Interface.
One of the struct frequently used in C# that is DateTime, a struct describing the date and time. You can see more about using date and time in C# at:
 
If struct appears as a parameter in a method, it is passed as a value. Meanwhile, if the class appears as a parameter in a method it is passed as a reference.
 
MyClass.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CSharpStructureTutorial
{
    class MyClass
    {

       public string name = "Abc";

       public MyClass(string name)
       {
           this.name = name;
       }
    }

}
MyStruct.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CSharpStructureTutorial
{
    struct MyStruct
    {
       public string name;

       public MyStruct(string name)
       {
           this.name = name;
       }
    }

}
MyTest.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CSharpStructureTutorial
{
    class MyTest
    {
        private static void passToMe(MyClass myClass, MyStruct myStruct)
        {
            // Change value for name field.
            myClass.name = "New Name";
 
            // Change value for name field.
            myStruct.name = "New Name";
        }

        public static void Main(string[] args) 
        {
            MyClass myClass = new MyClass("Abc");
            MyStruct myStruct = new MyStruct("Abc");

            Console.WriteLine("Before pass to method");
            Console.WriteLine("myClass.name = " + myClass.name);// Abc
            Console.WriteLine("myStruct.name = " + myStruct.name);// Abc

            Console.WriteLine("Pass to method");

            // myStruct passed to the method is a copy.
            // (Not the original object).
            passToMe(myClass, myStruct);

 
            Console.WriteLine("myClass.name = " + myClass.name); // New Name
            Console.WriteLine("myStruct.name = " + myStruct.name);// Abc

            Console.Read();

        }
        
    }

}
Running the example:

3- Constructor of Struct

Struct can have Constructors but do not have Destructor 
Here are  few notes for the Constructor:
  1. You can not write a default constructor (no parameters) for struct.
  2. In the constructor you must assign values to all fields that don't have value.

4- Methods and properties of struct

Struct can have methods and properties, and because Struct do not inherit, therefore, all its modes and  properties are not allowed to be abstract.
Book.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CSharpStructureTutorial
{
    struct Book
    {

        private string title;
        private string author;

        // Property
        public string Title
        {
            get
            {
                return this.title;
            }
            set
            {
                this.title = value;
            }
        }

        // Property
        public string Author
        {
            get
            {
                return this.author;
            }
        }

        // Constructor.
        public Book(string title, string author)
        {
            this.title = title;
            this.author = author;
        }

        // Method.
        public string GetInfo()
        {
            return "Book Title: " + this.title + ", Author: " + this.author;
        }
 
    }

}