The 30-Day .NET Challenge - Day 23: Span<T> over Arrays

Optimization involves choosing Span<T> over Arrays for manipulating memory regions. Discover a better approach using Spans on Day 23 of our 30-Day .NET Challenge.

This article demonstrates the use of Span<T> for optimizing memory management, highlighting the performance benefits.

Learning Objectives

• Drawbacks of the array in memory management
• Efficiency of Spans

Prerequisites for Developers

• Basic understanding of C# programming language.

Getting Started

The drawbacks of Arrays

Generally, developers use an array to store sequences of elements in continuous memory locations. Arrays are quite simple and easy to understand.

A code snippet of the byte array is shown below:

    // Bad way: Using arrays may lead to unnecessary memory allocations and copying
    byte[] data = GetData();
    ProcessData(data);

The problem with the above code is that it may lead to unnecessary memory allocations and copying because GetData creates a new array each time. The aforementioned code block will degrade the performance of the applications that require high data processing or applications that have limited memory resources.

Efficiency of Spans

Please find below the refactored version of the previous code snippet.

    // Good way: Using Span<T> avoids additional memory allocation and copying
    byte[] data = GetData();
    Span<byte> dataSpan = data.AsSpan();
    ProcessData(dataSpan);

The Span<T> provides a type-safe and memory-safe view of contiguous memory regions without worrying about the copy issue highlighted previously. Using the AsSpan() method creates a view of the original array without copying or creating a new memory each time.

Complete Code

Create another class named SpanOverArrayand add the following code snippet:

    public static class SpanOverArray
    {
        public static void ProcessData(byte[] data)
        {
            Console.WriteLine("Processing byte array:");
            foreach (var b in data)
            {
                Console.Write($"{b} ");
            }
            Console.WriteLine("\n");
        }
    
        public static void ProcessData(Span<byte> dataSpan)
        {
            Console.WriteLine("Processing Span<byte>:");
            foreach (var b in dataSpan)
            {
                Console.Write($"{b} ");
            }
            Console.WriteLine("\n");
        }
    }

Execute from the main method as follows

    #region Day 23: Span Over Arrays
    static string ExecuteDay23()
    {
    
        byte[] largeData = new byte[100]; // Simulate a large data set
        Random rng = new Random();
        rng.NextBytes(largeData); // Populate with random bytes
    
        // Process using array slice
        byte[] slice = new byte[10]; // Creating a new array for the slice
        Array.Copy(largeData, 10, slice, 0, 10); // Copying data
        SpanOverArray.ProcessData(slice);
    
        // Process using Span<T>
        Span<byte> span = largeData.AsSpan(10, 10); // Creating a span starting at index 10
        SpanOverArray.ProcessData(span);
        return "Executed Day 23 successfully..!!";
    }
    
    #endregion

Console Output

    Processing byte array:
    75 20 132 37 218 170 182 227 224 146
    
    Processing Span<byte>:
    75 20 132 37 218 170 182 227 224 146

Thank you for being a part of the C# community! Before you leave:

• Follow on: Youtube | X | LinkedIn | Dev.to
• Visit our other platforms: GitHub