Deconstruction In C#

Introduction

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)
    {
        // If id is 1000, assign specific values to the tuple elements
        name = "Mahesh Chand";
        title = "ADO.NET Programming";
        year = 2003;
    }

    // Return a tuple literal with the assigned values
    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 is Tuples In C# 7.0

References

References used to write this article.

• whats-new-in-csharp-7-0