Difference between readonly, private set, init and get only properties in C# .NET

Question

I am from Java springboot world and recently started learning C# 10 (.NET 6) for one of our clients requirement, initially I was facing a lot of pain understanding fundaments of C# 10, but now I am little comfortable, however I am not able to find good documentation, blogs or questions which provides comparison between similar features and some useful example.

I am currently trying to understand the difference between below, please also check if below is valid ?

public class Employee {
  public int Id {get;}; 
  public string Dept {get; set;};   
  public string FirstName {get; readonly set;}; 
  public string LastName {get; private set;}; 
  public string DateOfJoining {get; init;};
}

This is my guess, please review and help me understanding

public class Employee {
  public int Id {get;}; // hardcoded must be defined at the design time and can never change?
  public string Dept {get; set;};   //mutable - can be modified multiple times?
  public string FirstName {get; readonly set;}; // NOT SURE 
  public string LastName {get; private set;}; // NOT SURE 
  public string DateOfJoining {get; init;}; //immutable - can be set only once from constructor? 
}

https://learn.microsoft.com/en-us/dotnet/csharp/properties#access-control — CodeCaster, Dec 18 '22 at 13:18

Vivek Nuna · Answer 1 · 2022-12-18T13:16:08.413

First of all, there should not be a semicolon after the properties declaration.

this public string FirstName { get; readonly set; } is invalid, it will give compilation error. this test.Id = 1; will give compilation error as its readonly.

this test.Dept = "CS"; is allowed.

this test.LastName = "John"; is also not allowed, it will say set accessor not accessible.

this is allowed for init, not the one you have mentioned in your code.

public Test()
{
    DateOfJoining = "Today";
}

My class

internal class Test
{
    public int Id { get; }
    public string Dept { get; set; }
    //public string FirstName { get; readonly set; }
    public string LastName { get; private set; }
    public string DateOfJoining { get; init; }

    public Test()
    {
        DateOfJoining = "Today";
    }

}

check this also for the difference between init and readonly. Init is to allow assignment in object initialization as well online the readonly.

Difference between readonly, private set, init and get only properties in C# .NET

1 Answers1