In C # what does ": this" mean

Question

I met this C # bit at this link

I can not understand this line ...

public StockTickerHub() : this(StockTicker.Instance) { } 

It is a bit like inheriting from a base class, but I have never seen this like before.

 using System; using System.Collections.Generic; using System.Linq; using System.Web; using Microsoft.AspNet.SignalR; using Microsoft.AspNet.SignalR.Hubs; namespace SignalR.StockTicker { [HubName("stockTickerMini")] public class StockTickerHub : Hub { private readonly StockTicker _stockTicker; public StockTickerHub() : this(StockTicker.Instance) { } public StockTickerHub(StockTicker stockTicker) { _stockTicker = stockTicker; } public IEnumerable<Stock> GetAllStocks() { return _stockTicker.GetAllStocks(); } } } 

Answer 1

It calls another constructor of the same class.

 public class Foo { public Foo() : this (1) { } public Foo(int num) { } } 

Calling new Foo() calls Foo(1) .

Further information: http://www.dotnetperls.com/this-constructor

Answer 2

this(StockTicker.Instance) starts another class constructor:

Using Constructors (C # Programming Guide) :

A constructor can call another constructor in the same using the this . Like base , it can be used with or without parameters, and any parameters in the constructor are available as parameters to this or as part of an expression.

Answer 3

It calls another constructor