Friday, January 27, 2017

C# 7 Features - out variable initialization

In my previous article, we discussed about the concept of local functions in C# 7.0. In this article, we will see another feature related to the use of out type variables. 
Out variables are not new in C# and provide a big advantage of how we can return multiple values from a method. However, in order to pass a out type variable as a method parameter, we have to declare it first and then pass it into the method parameter, with out keyword. Something like the following: 
  1. static void Main(string[] args)  
  2. {  
  4.             int userId;  
  5.             string userName;  
  6.             GetDetails(out userId, out userName);  
  8.             Console.ReadKey();  
  9. }  
  10. public static void GetDetails(out Int32 UserId, out string Username)  
  11. {  
  12.             UserId = 12;  
  13.             Username = "Test User";  
  14. }  
However, in C# 7.0, we can declare the variable at the time of passing it as a method parameter, when method is being called. This means the following code will work fine in C# 7.0. 
  1. static void Main(string[] args)  
  2. {  
  3.             GetDetails(out int userId, out string userName);  
  4.             Console.ReadKey();  
  5. }  
Also, now we can have the out variable being declared as of var type, when passed as method parameter. So following code is valid and works fine in C# 7.0, which did not worked in earlier versions of C#. 
  1. static void Main(string[] args)  
  2.         {  
  3.             GetDetails(out var userId, out var userName);  
  4.             Console.ReadKey();  
  5.         }  
Hope you enjoyed reading it. Happy coding...!!!

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