C# - init vs private set vs get only property

Question

Hello,

What are the differences between init vs private set vs get only property in C#?

Thank you

    class Book
    {
        public string PrivateTitle { get; private set; }
        public string getOnlyTitle { get; }
        public string initTitle { get; init; }
    }

Answer 1

Best to read Microsoft Learn on init then read the following for private vs init.

For all examples

public enum Gender  
{  
    Female,  
    Male,  
    Other  
}  

Here is a record example which is immutable except for the primary key.

public record PersonRecord   
{  
    public int Id { get; set; }  
    public string FirstName { get; init; }  
    public string MiddleName { get; init; }  
    public string LastName { get; init; }  
    public Gender Gender { get; init; }  
    public DateTime? Modified { get; init; }  
}  

Usage

PersonRecord personRecord = new ()  
{  
    Id = 1,   
    FirstName = "Karen",   
    MiddleName = "",   
    LastName = "Payne",   
    Gender = Gender.Female,   
    Modified = DateTime.Now  
};  

Or make one property immutable

public class PersonClass  
{  
    public int Id { get; set; }  
    public string FirstName { get; set; }  
    public string MiddleName { get; set; }  
    public string LastName { get; set; }  
    public Gender Gender { get; init; }  
    public DateTime? Modified { get; set; }  
}  

Usage

PersonClass personClass = new()  
{  
    Id = 1,  
    FirstName = "Karen",  
    MiddleName = "",  
    LastName = "Payne",  
    Gender = Gender.Female,  
    Modified = DateTime.Now  
};  

Tweak Gender to private set.

public class PersonClass  
{  
    public int Id { get; set; }  
    public string FirstName { get; set; }  
    public string MiddleName { get; set; }  
    public string LastName { get; set; }  
    public Gender Gender { get; private set; }  
    public DateTime? Modified { get; set; }  
}  

Classic get only

public class PersonClass  
{  
    public int Id { get; set; }  
    public string FirstName { get; set; }  
    public string MiddleName { get; set; }  
    public string LastName { get; set; }  
    public Gender Gender { get; init; }  
    public DateTime? Modified { get; set; }  
  
    public string FullName  
    {  
        get  
        {  
            return $"{FirstName} {MiddleName} {LastName}";  
        }  
    }  
  
}  

Expression body member get

public class PersonClass  
{  
    public int Id { get; set; }  
    public string FirstName { get; set; }  
    public string MiddleName { get; set; }  
    public string LastName { get; set; }  
    public Gender Gender { get; init; }  
    public DateTime? Modified { get; set; }  
    public string FullName => $"{FirstName} {MiddleName} {LastName}";  
}  

And for completness

public record Person1(string FirstName, string MiddleName, string LastName);  

Used (read-only)

Person1 person1 = new("Karen", "","Payne");