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Span is a type introduced in C# 7.2 as part of the Span
Span in C# allows developers to work with memory directly without resorting to traditional heap allocations. It offers a way to create slices of memory from existing arrays or other memory sources, eliminating the need for additional memory copies.
One of the standout features of C# Span is its zero-copy abstractions. Instead of duplicating data, Span provides a way to reference existing memory efficiently. This is particularly beneficial for scenarios where copying large amounts of data would be impractical or too costly.
While C# has traditionally been a high-level, safe language, Span introduces a degree of low-level memory manipulation akin to working with pointers in languages like C or C++. Developers can perform pointer-like operations without sacrificing the safety and managed nature of C#.
Despite its capabilities for low-level memory access, C# Span remains immutable. This means that, while it allows manipulation of memory, it enforces safety by preventing unintended modifications.
using System;
class Program
{
void Main()
{
int[] array = { 1, 2, 3, 4, 5 };
// Create a span that points to the entire array
Span<int> span = array;
// Modify the data using the span
span[2] = 10;
// Print the modified array
foreach (var item in array)
{
Console.WriteLine(item);
}
}
}
using System;
class Program
{
void Main()
{
int[] array = { 1, 2, 3, 4, 5 };
// Create a span that points to the entire array
Span<int> span = array;
// Modify the data using the span
span[2] = 10;
// Print the modified array
foreach (var item in array)
{
Console.WriteLine(item);
}
}
}
While Span
Here are some key points.
As the name suggests, ReadOnlySpan
Like Span
Like Span
As with Span
ReadOnlySpan
using System;
class Program
{
static void Main()
{
int[] array = { 1, 2, 3, 4, 5 };
// Create a read-only span that points to the entire array
ReadOnlySpan<int> readOnlySpan = array;
// Access and print the data through the read-only span
foreach (var item in readOnlySpan)
{
Console.WriteLine(item);
}
// Note: The following line would result in a compilation error since readOnlySpan is read-only.
// readOnlySpan[2] = 10;
}
}
using System;
class Program
{
static void Main()
{
int[] array = { 1, 2, 3, 4, 5 };
// Create a read-only span that points to the entire array
ReadOnlySpan<int> readOnlySpan = array;
// Access and print the data through the read-only span
foreach (var item in readOnlySpan)
{
Console.WriteLine(item);
}
// Note: The following line would result in a compilation error since readOnlySpan is read-only.
// readOnlySpan[2] = 10;
}
}
There are many different ways to create ReadOnlySpan and work with it. Below are some examples.
string msg = "Hello, World!";
ReadOnlySpan<char> span1 = msg.AsSpan();
// Read-only manipulation
char firstChar = span1[0];
Console.WriteLine(firstChar); // Outputs: H
string msg = "Hello, World!";
ReadOnlySpan<char> span1 = msg.AsSpan();
// Read-only manipulation
char firstChar = span1[0];
Console.WriteLine(firstChar); // Outputs: H
Use Slice on the ReadOnlySpan
ReadOnlySpan<char> substringSpan = spanFromString.Slice(startIndex, length);
ReadOnlySpan<char> substringSpan = spanFromString.Slice(startIndex, length);
Pass ReadOnlySpan
void ProcessSubstringfromReadOnlySpan(ReadOnlySpan<char> substring)
{
// Perform operations on the substring
}
// Usage
ProcessSubstringfromReadOnlySpan(spanFromString.Slice(startIndex, length));
void ProcessSubstringfromReadOnlySpan(ReadOnlySpan<char> substring)
{
// Perform operations on the substring
}
// Usage
ProcessSubstringfromReadOnlySpan(spanFromString.Slice(startIndex, length));
ReadOnlySpan
int index = stringSpan.IndexOf('W');
int index = stringSpan.IndexOf('W');
ReadOnlySpan
using (var memmf = MemoryMappedFile.CreateFromFile("data.bin"))
{
using (var accessor = memmf.CreateViewAccessor())
{
ReadOnlySpan<byte> dataSpan;
accessor.Read(0, out dataSpan);
// Process data directly from the memory-mapped file
ProcessData(dataSpan);
}
}
using (var memmf = MemoryMappedFile.CreateFromFile("data.bin"))
{
using (var accessor = memmf.CreateViewAccessor())
{
ReadOnlySpan<byte> dataSpan;
accessor.Read(0, out dataSpan);
// Process data directly from the memory-mapped file
ProcessData(dataSpan);
}
}
ReadOnlySpan
// Replace a character in a substring without creating a new string
spanFromString.Slice(startIndex, length).CopyTo(newSpan);
// Replace a character in a substring without creating a new string
spanFromString.Slice(startIndex, length).CopyTo(newSpan);
When working with external libraries or APIs that operate on character spans.
void ExternalApiMethod(ReadOnlySpan<char> data)
{
// Call the external API with the character span
}
// Usage
ExternalApiMethod(spanFromString.Slice(startIndex, length));
void ExternalApiMethod(ReadOnlySpan<char> data)
{
// Call the external API with the character span
}
// Usage
ExternalApiMethod(spanFromString.Slice(startIndex, length));
ReadOnlySpan
While Span in C# is a powerful feature with numerous advantages, it does come with certain limitations and considerations, particularly in the context of contiguous and non-contiguous memory. Let's explore these limitations:
Span
Since Span
Span
Span
While Span
While Span
ReadOnlySpan
Certain data structures or scenarios that rely on non-contiguous memory may not align well with ReadOnlySpan
In situations involving non-contiguous memory, particularly those requiring intricate pointer arithmetic, ReadOnlySpan
Similar to contiguous memory, it's important to note that not all APIs or libraries may directly support non-contiguous memory represented by ReadOnlySpan
In C#, Span can be effectively used with unmanaged memory to perform memory-related operations in a controlled and efficient manner. Unmanaged memory refers to memory that is not managed by the .NET runtime's garbage collector, and it often involves using native memory allocations and deallocations. Here's how Span can be utilized with unmanaged memory in C#.
To allocate unmanaged memory, you can use the System.Runtime.InteropServices.MemoryMarshal class. The Marshal.AllocHGlobal method allocates memory and returns a pointer to the allocated block. The memory allocated or memory address is held in an unmanagedMemory pointer and will have read-write access. The contiguous regions of memory can be easily accessed.
using System;
using System.Runtime.InteropServices;
class Program
{
static void Main()
{
const int bufferSize = 100;
IntPtr unmanagedMemory = Marshal.AllocHGlobal(bufferSize);
// Create a Span from the unmanaged memory
Span<byte> span = new Span<byte>(unmanagedMemory.ToPointer(), bufferSize);
// Use the Span as needed...
// Don't forget to free the unmanaged memory when done
Marshal.FreeHGlobal(unmanagedMemory);
}
}
using System;
using System.Runtime.InteropServices;
class Program
{
static void Main()
{
const int bufferSize = 100;
IntPtr unmanagedMemory = Marshal.AllocHGlobal(bufferSize);
// Create a Span from the unmanaged memory
Span<byte> span = new Span<byte>(unmanagedMemory.ToPointer(), bufferSize);
// Use the Span as needed...
// Don't forget to free the unmanaged memory when done
Marshal.FreeHGlobal(unmanagedMemory);
}
}
In the above source code, we allocate a block of unmanaged memory using Marshal.AllocHGlobal and then create a Span
Span provides methods like Slice, CopyTo, and ToArray that can be used for copying data between managed and unmanaged memory efficiently.
using System;
using System.Runtime.InteropServices;
class Program
{
static void Main()
{
// Managed array to copy data from
int[] sourceArray = { 1, 2, 3, 4, 5 };
// Allocate unmanaged memory for the destination data
IntPtr destinationPointer = MemoryMarshal.Allocate<int>(sourceArray.Length);
try
{
// Create a Span<int> from the source array
Span<int> sourceSpan = sourceArray;
// Create a Span<int> from the allocated unmanaged memory
Span<int> destinationSpan = MemoryMarshal.Cast<int, byte>(destinationPointer, sourceArray.Length);
// Copy data from the source Span<int> to the destination Span<int>
sourceSpan.CopyTo(destinationSpan);
// Print the values in the destination memory
Console.WriteLine("Values in the destination memory:");
foreach (var value in destinationSpan)
{
Console.Write($"{value} ");
}
}
finally
{
// Deallocate the unmanaged memory when done
MemoryMarshal.Free(destinationPointer);
}
}
}
using System;
using System.Runtime.InteropServices;
class Program
{
static void Main()
{
// Managed array to copy data from
int[] sourceArray = { 1, 2, 3, 4, 5 };
// Allocate unmanaged memory for the destination data
IntPtr destinationPointer = MemoryMarshal.Allocate<int>(sourceArray.Length);
try
{
// Create a Span<int> from the source array
Span<int> sourceSpan = sourceArray;
// Create a Span<int> from the allocated unmanaged memory
Span<int> destinationSpan = MemoryMarshal.Cast<int, byte>(destinationPointer, sourceArray.Length);
// Copy data from the source Span<int> to the destination Span<int>
sourceSpan.CopyTo(destinationSpan);
// Print the values in the destination memory
Console.WriteLine("Values in the destination memory:");
foreach (var value in destinationSpan)
{
Console.Write($"{value} ");
}
}
finally
{
// Deallocate the unmanaged memory when done
MemoryMarshal.Free(destinationPointer);
}
}
}
In this example:
MemoryMarshal.Allocate
When dealing with unmanaged memory, you may also use unsafe code with pointers. In such cases, you can obtain a pointer from the Span using the Unsafe.AsPointer() method.
using System;
using System.Runtime.InteropServices;
class Program
{
static void Main()
{
const int bufferSize = 100;
IntPtr unmanagedMemory = Marshal.AllocHGlobal(bufferSize);
// Create a Span from the unmanaged memory
Span<byte> span = new Span<byte>(unmanagedMemory.ToPointer(), bufferSize);
// Use unsafe code to work with pointers
// ref t
unsafe
{
byte* pointer = (byte*)Unsafe.AsPointer(ref struct MemoryMarshal.GetReference(span));
// Use the pointer as needed...
}
// Don't forget to free the unmanaged memory when done
Marshal.FreeHGlobal(unmanagedMemory);
}
}
using System;
using System.Runtime.InteropServices;
class Program
{
static void Main()
{
const int bufferSize = 100;
IntPtr unmanagedMemory = Marshal.AllocHGlobal(bufferSize);
// Create a Span from the unmanaged memory
Span<byte> span = new Span<byte>(unmanagedMemory.ToPointer(), bufferSize);
// Use unsafe code to work with pointers
// ref t
unsafe
{
byte* pointer = (byte*)Unsafe.AsPointer(ref struct MemoryMarshal.GetReference(span));
// Use the pointer as needed...
}
// Don't forget to free the unmanaged memory when done
Marshal.FreeHGlobal(unmanagedMemory);
}
}
In this example, we use the Unsafe.AsPointer method to obtain a pointer from the Span. This allows us to use unsafe code when working with pointers directly.
Remember, when working with unmanaged memory, it's crucial to manage the allocation and deallocation properly to avoid memory leaks. Always free unmanaged memory using appropriate methods, such as Marshal.FreeHGlobal(). Additionally, exercise caution when using unsafe code, as it can introduce potential security risks if not handled properly.
Using Span in conjunction with asynchronous method calls in C# is a powerful combination, especially when dealing with large amounts of data or I/O operations. The goal is to handle asynchronous operations without unnecessary copying of data efficiently. Let's explore how you can leverage Span in asynchronous scenarios:
When dealing with asynchronous I/O operations, such as reading or writing data to a stream, you can use Memory
async Task ProcessDataAsync(Stream stream)
{
const int bufferSize = 4096;
byte[] buffer = new byte[bufferSize];
while (true)
{
int bytesRead = await stream.ReadAsync(buffer.AsMemory());
if (bytesRead == 0)
break;
// Process the data using Span without unnecessary copying
ProcessData(buffer.AsSpan(0, bytesRead));
}
}
void ProcessData(Span<byte> data)
{
// Perform operations on the data
}
async Task ProcessDataAsync(Stream stream)
{
const int bufferSize = 4096;
byte[] buffer = new byte[bufferSize];
while (true)
{
int bytesRead = await stream.ReadAsync(buffer.AsMemory());
if (bytesRead == 0)
break;
// Process the data using Span without unnecessary copying
ProcessData(buffer.AsSpan(0, bytesRead));
}
}
void ProcessData(Span<byte> data)
{
// Perform operations on the data
}
In this example, the ReadAsync method asynchronously reads data from a stream into the buffer. The ProcessData method then processes the data directly from the Span
Similar to I/O operations, when dealing with asynchronous file operations, you can use Span to efficiently process data without additional copying.
async Task ProcessFileAsync(string filePath)
{
const int bufferSize = 4096;
using (FileStream fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read))
{
byte[] buffer = new byte[bufferSize];
while (true)
{
int bytesRead = await fileStream.ReadAsync(buffer.AsMemory());
if (bytesRead == 0)
break;
// Process the data using Span without unnecessary copying
ProcessData(buffer.AsSpan(0, bytesRead));
}
}
}
void ProcessData(Span<byte> data)
{
// Perform operations on the data
}
async Task ProcessFileAsync(string filePath)
{
const int bufferSize = 4096;
using (FileStream fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read))
{
byte[] buffer = new byte[bufferSize];
while (true)
{
int bytesRead = await fileStream.ReadAsync(buffer.AsMemory());
if (bytesRead == 0)
break;
// Process the data using Span without unnecessary copying
ProcessData(buffer.AsSpan(0, bytesRead));
}
}
}
void ProcessData(Span<byte> data)
{
// Perform operations on the data
}
Here, the ReadAsync method reads data from a file stream into the buffer, and the ProcessData method processes the data directly from the Span
When working with asynchronous tasks that produce or consume data, you can use Memory
async Task<int> ProcessDataAsync(int[] data)
{
// Asynchronous processing of data
await Task.Delay(1000);
// Returning the length of the processed data
return data.Length;
}
async Task Main()
{
int[] inputData = Enumerable.Range(1, 1000).ToArray();
// Process the data asynchronously without copying
int processedLength = await ProcessDataAsync(inputData.AsMemory());
Console.WriteLine($"Processed data length: {processedLength}");
}
async Task<int> ProcessDataAsync(int[] data)
{
// Asynchronous processing of data
await Task.Delay(1000);
// Returning the length of the processed data
return data.Length;
}
async Task Main()
{
int[] inputData = Enumerable.Range(1, 1000).ToArray();
// Process the data asynchronously without copying
int processedLength = await ProcessDataAsync(inputData.AsMemory());
Console.WriteLine($"Processed data length: {processedLength}");
}
In this example, the ProcessDataAsync method processes the data asynchronously and returns the length of the processed data without requiring additional copies.
IronPDF library overview is the latest C# PDF library from Iron Software which can be used to generate beautiful PDF documents on the fly dynamically using C# code. IronPDF provides a variety of features such as PDF generation from HTML, converting HTML content to PDF, merging or splitting PDF files, etc.
IronPDF’s main feature is its HTML to PDF functionality, which preserves layouts and styles. It can generate PDFs from web content, making it great for reports, invoices, and documentation. This tool supports converting HTML files, URLs, and HTML strings to PDF files.
using IronPdf;
class Program
{
static void Main(string[] args)
{
var renderer = new ChromePdfRenderer();
// 1. Convert HTML String to PDF
var htmlContent = "<h1>Hello, IronPDF!</h1><p>This is a PDF from an HTML string.</p>";
var pdfFromHtmlString = renderer.RenderHtmlAsPdf(htmlContent);
pdfFromHtmlString.SaveAs("HTMLStringToPDF.pdf");
// 2. Convert HTML File to PDF
var htmlFilePath = "path_to_your_html_file.html"; // Specify the path to your HTML file
var pdfFromHtmlFile = renderer.RenderHtmlFileAsPdf(htmlFilePath);
pdfFromHtmlFile.SaveAs("HTMLFileToPDF.pdf");
// 3. Convert URL to PDF
var url = "http://ironpdf.com"; // Specify the URL
var pdfFromUrl = renderer.RenderUrlAsPdf(url);
pdfFromUrl.SaveAs("URLToPDF.pdf");
}
}
using IronPdf;
class Program
{
static void Main(string[] args)
{
var renderer = new ChromePdfRenderer();
// 1. Convert HTML String to PDF
var htmlContent = "<h1>Hello, IronPDF!</h1><p>This is a PDF from an HTML string.</p>";
var pdfFromHtmlString = renderer.RenderHtmlAsPdf(htmlContent);
pdfFromHtmlString.SaveAs("HTMLStringToPDF.pdf");
// 2. Convert HTML File to PDF
var htmlFilePath = "path_to_your_html_file.html"; // Specify the path to your HTML file
var pdfFromHtmlFile = renderer.RenderHtmlFileAsPdf(htmlFilePath);
pdfFromHtmlFile.SaveAs("HTMLFileToPDF.pdf");
// 3. Convert URL to PDF
var url = "http://ironpdf.com"; // Specify the URL
var pdfFromUrl = renderer.RenderUrlAsPdf(url);
pdfFromUrl.SaveAs("URLToPDF.pdf");
}
}
IronPDF can be installed using the NuGet package manager for IronPDF console or using the Visual Studio package manager.
dotnet add package IronPdf
// Or
Install-Package IronPdf
dotnet add package IronPdf
// Or
Install-Package IronPdf
using System;
class Program
{
static void Main()
{
Console.WriteLine("Generating PDF using IronPDF.");
var displayFirstName = "<p>First Name is Joe</p>".AsSpan();
var displayLastName = "<p>First Name is Doe</p>".AsSpan();
var displayAddress = "<p>12th Main, 7Th Cross, New York</p>".AsSpan();
var start = @"<!DOCTYPE html>
<html>
<body>".AsSpan();
var end = @"<!DOCTYPE html>
<html>
<body>";
var content = string.Concat(start, displayFirstName, displayLastName, string.Concat(displayAddress, end));
var pdfDocument = new ChromePdfRenderer();
pdfDocument.RenderHtmlAsPdf(content).SaveAs("span.pdf");
}
}
using System;
class Program
{
static void Main()
{
Console.WriteLine("Generating PDF using IronPDF.");
var displayFirstName = "<p>First Name is Joe</p>".AsSpan();
var displayLastName = "<p>First Name is Doe</p>".AsSpan();
var displayAddress = "<p>12th Main, 7Th Cross, New York</p>".AsSpan();
var start = @"<!DOCTYPE html>
<html>
<body>".AsSpan();
var end = @"<!DOCTYPE html>
<html>
<body>";
var content = string.Concat(start, displayFirstName, displayLastName, string.Concat(displayAddress, end));
var pdfDocument = new ChromePdfRenderer();
pdfDocument.RenderHtmlAsPdf(content).SaveAs("span.pdf");
}
}
In this example, we are using Span along with IronPDF to generate a PDF document.
Output:
Generated PDF:
IronPDF license information. This key needs to be placed in appsettings.json.
"IronPdf.LicenseKey": "your license key"
"IronPdf.LicenseKey": "your license key"
Provide your email to get a trial license.
Span
Please visit IronPDF's Quick-Start Documentation Page page.