In my previous article, I 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 an out type variable as a method parameter, we have to declare it first and then pass it into the method parameter with out keyword, which is shown below.
  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 the method is being called. This means the code given below 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, we can have the out variable being declared as of var type, when passed as method parameter. Hence, the code given below is valid and works fine in C# 7.0, which did not work in earlier versions of C#.
  1. static void Main(string[ ] args)
  2. {
  3. GetDetails(out var userId, out var userName);
  4. Console.ReadKey();
  5. }
I hope you enjoyed reading it. Happy coding.