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. {  
3.   
4.             int userId;  
5.             string userName;  
6.             GetDetails(out userId, out userName);  
7.   
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...!!!