Deconstruction In C# 7.0

Deconstruction is a process of splitting a variable value into parts and storing them into new variables. This could be useful when a variable stores multiple values such as a tuple.

Let’s take a look at the code sample in Listing 1. In this code, method GetATuple returns a tuple with three values.

// This method returns a tuple with three values
(string name, string title, long year) GetATuple(long id)
{
string name = string.Empty;
string title = string.Empty;
long year = 0;
if (id == 1000)
{
name = "Mahesh Chand";
title = "ADO.NET Programming";
year = 2003;
}
// tuple literal

return (name, title, year);

}

Listing 1.

The code snippet in Listing 2 calls the GetATuple method and displays the return values on the console.

(string authorName, string bookTitle, long pubYear)
= GetATuple(1000);
Console.WriteLine("Author: {0} Book: {1} Year: {2}", authorName, bookTitle, pubYear);

Listing 2.

The code in Listing 2 can be deconstructed as the code in Listing 3, where three var types are used to store the return values.

(var authorName, var bookTitle, var pubYear) = GetATuple(1000);
Console.WriteLine("Author: {0} Book: {1} Year: {2}", authorName, bookTitle, pubYear);

Listing 3.

The code in Listing 3 can also be replaced by the following syntax in Listing 4.

var (authorName, bookTitle, pubYear) = GetATuple(1000);
Console.WriteLine("Author: {0} Book: {1} Year: {2}", authorName, bookTitle, pubYear);

Listing 4.

Summary

In this article, we learned the deconstruction process introduced in C# 7.0.

Next C# 7.0 Feature >>  Tuples In C# 7.0

References

References used to write this article,

https://blogs.msdn.microsoft.com/dotnet/2016/08/24/whats-new-in-csharp-7-0/