5 Easy Ways to Return Multiple Values in C#

In this article, we will explore advanced strategies for creating functions that return multiple values in C#. We will dive into various techniques such as using tuples, out parameters, value tuples, custom classes/structs, ref returns, pattern matching, async methods, records, dynamic objects, generics, extension methods, local functions, and discards. Each method provides a unique approach to handling multiple return values, offering flexibility and efficiency in your code.

Using Tuples

Tuples in C# provide a way to return multiple values without the need for defining new classes or structures. Let’s explore an example showcasing the usage of tuples to calculate and return the sum and product of two numbers:

<span class="hljs-keyword">public</span> (<span class="hljs-built_in">int</span> Sum, <span class="hljs-built_in">int</span> Product) Calculate(<span class="hljs-built_in">int</span> a, <span class="hljs-built_in">int</span> b)
{
    <span class="hljs-keyword">return</span> (a + b, a * b);
}

<span class="hljs-comment">// How to use tuples</span>
<span class="hljs-keyword">var</span> result = Calculate(<span class="hljs-number">2</span>, <span class="hljs-number">3</span>);
Console.WriteLine(<span class="hljs-string">$"Sum: <span class="hljs-subst">{result.Sum}</span>, Product: <span class="hljs-subst">{result.Product}</span>"</span>);

In the code above, the Calculate function employs tuples to efficiently return both the sum and product of the input numbers. Tuples offer a concise and straightforward way to handle multiple return values in a single data structure.

Real-life Example:

Consider a scenario where you need to calculate the total price and tax of a product in an e-commerce application. By utilizing tuples, you can return both values from the calculation function without the overhead of creating custom classes or structures.

Code Explanation:

• The Calculate method takes two integers a and b as input parameters.
• It calculates the sum of a and b using a + b and the product using a * b.
• The result is then returned as a tuple (Sum, Product) where Sum corresponds to the sum of the input numbers, and Product represents their product.
• When calling the Calculate function with values 2 and 3, the returned tuple is stored in the result variable.
• Finally, the [Console.WriteLine](https://www.bytehide.com/blog/console-writeline-csharp) statement displays the sum and product values extracted from the tuple using result.Sum and result.Product.

By leveraging tuples in your C# code, you can streamline the process of returning multiple values efficiently and elegantly.

Out Parameters

In certain cases, it becomes necessary to return additional information alongside the main return value from a method. This is where out parameters in C# prove to be valuable. Let’s explore a practical example involving a method that parses a date string and returns a DateTime object using an out parameter:

<span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-built_in">bool</span> <span class="hljs-title">TryParseDate</span>(<span class="hljs-params"><span class="hljs-built_in">string</span> dateString, <span class="hljs-keyword">out</span> DateTime date</span>)</span>
{
    <span class="hljs-keyword">return</span> DateTime.TryParse(dateString, <span class="hljs-keyword">out</span> date);
}

<span class="hljs-comment">// How to utilize out parameters</span>
<span class="hljs-keyword">if</span> (TryParseDate(<span class="hljs-string">"2024-02-19"</span>, <span class="hljs-keyword">out</span> DateTime resultDate))
{
    Console.WriteLine(<span class="hljs-string">$"Parsed Date: <span class="hljs-subst">{resultDate.ToShortDateString()}</span>"</span>);
}
<span class="hljs-keyword">else</span>
{
    Console.WriteLine(<span class="hljs-string">"Invalid Date"</span>);
}

In the provided code snippet, the TryParseDate function is designed to attempt parsing a given date string and return the corresponding DateTime object via the out parameter.

Real-life Example:

Imagine a situation in a finance application where user input needs to be validated, including date entries. By using an out parameter to return the parsed date, the application can ensure that the date format is correct and accessible for further processing.

Code Explanation:

• The TryParseDate method takes a string parameter representing a date in the dateString variable.
• The method attempts to parse the input string as a DateTime object using DateTime.TryParse.
• The parsed date result is returned through the out parameter named date, with the method returning a boolean indicating the success of the parsing operation.
• In the usage example, the TryParseDate function is called with the date string "2024-02-19", and the parsed DateTime value is retrieved in the resultDate variable.
• If the parsing is successful, the parsed date is displayed using resultDate.ToShortDateString(). Otherwise, an “Invalid Date” message is shown.

The use of out parameters in C# facilitates returning additional information from methods and enhances the flexibility and functionality of code that requires multiple return values.

Using ValueTuple for More Flexibility

ValueTuple in C# offers increased versatility for handling tuple operations, including deconstruction. Let’s delve into a practicable example demonstrating the utility of ValueTuple by creating a function that provides the dimensions of a geometrical shape in a ValueTuple structure:

<span class="hljs-keyword">public</span> (<span class="hljs-built_in">int</span>, <span class="hljs-built_in">int</span>) GetDimensions()
{
    <span class="hljs-keyword">return</span> (<span class="hljs-number">1024</span>, <span class="hljs-number">768</span>);
}

<span class="hljs-comment">// Deconstruction of ValueTuple</span>
<span class="hljs-keyword">var</span> (width, height) = GetDimensions();
Console.WriteLine(<span class="hljs-string">$"Width: <span class="hljs-subst">{width}</span>, Height: <span class="hljs-subst">{height}</span>"</span>);

In the provided code segment, we define a ValueTuple to represent the dimensions of a shape, showcasing how to deconstruct the tuple to access individual width and height values efficiently.

Real-life Example:

Consider an image processing application where different image sizes need to be retrieved and manipulated. By employing ValueTuple to return the width and height dimensions, developers can seamlessly extract and utilize these values for diverse image processing tasks.

Code Explanation:

• The GetDimensions method is implemented to return a ValueTuple representing the dimensions of a shape, specified as (1024, 768) in this instance.
• Through deconstruction, the width and height values from the returned ValueTuple are extracted and assigned to the variables width and height respectively.
• The extracted width and height values are then displayed using Console.WriteLine, presenting the dimensions of the shape accurately.

By leveraging ValueTuple in C# programming, one can streamline the handling of tuple operations, such as returning multiple values and deconstructing them for convenient access and manipulation. This feature contributes to code readability and enhances the flexibility of working with tuple data structures.

Returning a Custom Class or Struct

When handling intricate sets of interconnected data, creating a custom class or struct can enhance the clarity and organization of the code. Let’s delve into an example where we define a custom class named OperationResult to encapsulate the outcome of a calculation:

<span class="hljs-keyword">public</span> <span class="hljs-keyword">class</span> <span class="hljs-title">OperationResult</span>
{
    <span class="hljs-keyword">public</span> <span class="hljs-built_in">int</span> Sum { <span class="hljs-keyword">get</span>; <span class="hljs-keyword">set</span>; }
    <span class="hljs-keyword">public</span> <span class="hljs-built_in">int</span> Product { <span class="hljs-keyword">get</span>; <span class="hljs-keyword">set</span>; }
}

<span class="hljs-function"><span class="hljs-keyword">public</span> OperationResult <span class="hljs-title">PerformCalculation</span>(<span class="hljs-params"><span class="hljs-built_in">int</span> a, <span class="hljs-built_in">int</span> b</span>)</span>
{
    <span class="hljs-keyword">return</span> <span class="hljs-keyword">new</span> OperationResult { Sum = a + b, Product = a * b };
}

<span class="hljs-comment">// Utilizing the Custom Class</span>
<span class="hljs-keyword">var</span> result = PerformCalculation(<span class="hljs-number">5</span>, <span class="hljs-number">4</span>);
Console.WriteLine(<span class="hljs-string">$"Sum: <span class="hljs-subst">{result.Sum}</span>, Product: <span class="hljs-subst">{result.Product}</span>"</span>);

In the presented code snippet, we create a custom class OperationResult with properties to store the sum and product values resulting from a calculation operation.

Real-life Example:

Imagine a banking application where interest calculations need to be performed on user investments. By using a custom class like OperationResult to manage and return calculation outcomes, the code becomes more structured and easier to maintain.

Code Explanation:

• The OperationResult class is defined with properties Sum and Product to hold the calculated sum and product values.
• The PerformCalculation method computes the sum (a + b) and product (a * b) of two input integers and returns an instance of the OperationResult class initialized with these values.
• Upon invoking the PerformCalculation function with inputs 5 and 4, the returned result object contains the calculated sum and product values.
• The Console.WriteLine statement displays the sum and product values extracted from the result object, showcasing the encapsulation of multiple return values in a custom class.

By utilizing custom classes or structs for managing and returning complex data structures, developers can improve code readability and maintainability, particularly when dealing with multifaceted computation results.

Using Ref Return and Ref Locals

In scenarios where direct modifications to data are required without unnecessary copying, C# provides the concept of ref returns and ref locals. Let’s explore a practical example that demonstrates how to find and return a reference to a specific name within an array utilizing ref returns:

<span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">ref</span> <span class="hljs-built_in">string</span> <span class="hljs-title">FindName</span>(<span class="hljs-params"><span class="hljs-built_in">string</span>[] names, <span class="hljs-built_in">string</span> target</span>)</span>
{
    <span class="hljs-keyword">for</span> (<span class="hljs-built_in">int</span> i = <span class="hljs-number">0</span>; i &lt; names.Length; i++)
    {
        <span class="hljs-keyword">if</span> (names[i] == target)
        {
            <span class="hljs-keyword">return</span> <span class="hljs-keyword">ref</span> names[i]; <span class="hljs-comment">// Return a reference to the array element</span>
        }
    }

    <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> Exception(<span class="hljs-string">"Name not found"</span>);
}

<span class="hljs-comment">// How to apply ref return and ref locals</span>
<span class="hljs-built_in">string</span>[] names = { <span class="hljs-string">"Alice"</span>, <span class="hljs-string">"Bob"</span>, <span class="hljs-string">"Charlie"</span> };
<span class="hljs-keyword">ref</span> <span class="hljs-built_in">string</span> foundName = <span class="hljs-function"><span class="hljs-keyword">ref</span> <span class="hljs-title">FindName</span>(<span class="hljs-params">names, <span class="hljs-string">"Bob"</span></span>)</span>;
foundName = <span class="hljs-string">"Bobby"</span>; <span class="hljs-comment">// Directly modifies the array</span>
Console.WriteLine(<span class="hljs-built_in">string</span>.Join(<span class="hljs-string">", "</span>, names)); <span class="hljs-comment">// Outputs: Alice, Bobby, Charlie</span>

In the above code segment, the FindName method searches for a specific name within an array and returns a reference to that element to allow direct manipulation of the array contents.

Real-life Example:

Consider a task management application where users can update the status of tasks. Using ref returns can facilitate quick and direct updates to task properties without additional memory overhead.

Code Explanation:

• The FindName function searches for the target name within the names array and returns a reference to the matching element using the ref keyword.
• If the target name is found, the reference to that array element is returned for direct modification.
• In the practical implementation, the name “Bob” is located in the names array, and the reference to this element is assigned to foundName via the FindName method.
• Updating foundName to “Bobby” directly modifies the array element, showcasing the immediate impact of ref returns on the data structure.
• The Console.WriteLine statement displays the updated array elements, demonstrating the direct modification of the array contents.

By leveraging ref returns and ref locals in C#, developers can efficiently manage and update data structures, leading to enhanced performance and reduced memory consumption when working with large datasets.

Conclusion

Implementing these methods not only enhances code readability and maintainability but also offers flexibility and efficiency in handling multiple return values. It’s essential for developers to understand the strengths and use cases of each technique to leverage them effectively in their projects.

Overall, mastering the art of returning multiple values in C# opens up a world of possibilities and empowers developers to write cleaner, more expressive code. Experimenting with these techniques and incorporating them into your coding practices will undoubtedly elevate your C# programming skills.

Comments

[craig mcinne]

Code formatting broken on this one too.