A structure type (or struct type) is a value type that can encapsulate data and related functionality. struct keyword is used to define a structure type.

Typically, you use structure types to design small data-centric types that provide little or no behavior.
Structure types have value semantics. That is, a variable of a structure type contains an instance of the type.

Difference between struct and class

`struct`	`class`
`struct` cannot be inherited	`class` can be inherited
`struct` cannot have default constructor	`class` can have default constructor
Value types (of a `struct`) that are allocated on the stack or on inline (more performant)	Reference types (of a `class`) are allocated on the heap and garbage-collected
A struct contains the entire struct, with all its fields.	A `class` contains pointer to its fields
Value types (of a `struct`) always contains a value	Reference types (of a `class`) can contain a null-reference
`struct` are used for small data structures	`class` are used for complex data structures
Copying the contents of a value type variable (a `struct`) copies the entire contents into the new variable, making the two distinct	Copying the contents of a reference type variable (a `class` ) into another variable copies the reference, the two pointing to the same storage
After the copy, changes to one won’t affect the other	After the copy, changes to one will affect the other

Creation

Without constructor

  struct Employee {
    public int id;

    public void getId(int id) {
      Console.WriteLine("Employee Id: " + id);
    }
  }

  Employee emp;
  emp.id = 1;
  Console.WriteLine(emp.id);

With a constructor

  struct Employee {
    public int id;

    public Employee(int employeeId) {
      id = employeeId;
    }
  }

  Employee emp = new Employee(1);
  Console.WriteLine(emp.id);

Creation with inheritance

A struct can’t be inherited but can inherit from an interface.

  public interface Person
  {  
    string Name { get; set; }
    double Age { get; set; }
    double GetLifeExpectancy();    
  }

  struct Employee: Person
  {
    public const int hoursWorked = 35;
    public string Name { get; set; }
    public double Age { get; set; }
    public int id;

    public Employee(int employeeId, string name, double age) {
      id = employeeId;
      Name = name;
      Age = age;
    }

    public double GetLifeExpectancy() {
      return(80D - age);
    }
  }

  Employee employee = new Employee(1, "Henry", 33);
  Console.WriteLine(emp.GetLifeExpectancy()); // 50

Ressources

See:

Revision