public static int Add(in int number1, in int number2)
{
   number1 = 5; // Cannot assign to variable 'in int' because it is a readonly variable
   return number1 + number2;
}

<ItemGroup>
     <PackageReference Include="BenchmarkDotNet" Version="0.10.12" />
</ItemGroup>

using BenchmarkDotNet.Attributes;

namespace CS72Tests
{
    public struct Input
    {
        public decimal Number1;
        public decimal Number2;
    }

    [MemoryDiagnoser]
    public class InBenchmarking
    {
        const int loops = 50000000;
        Input inputInstance = new Input();

        [Benchmark(Baseline = true)]
        public decimal RunNormalLoop_Pass_By_Value()
        {
            decimal result = 0M;
            for (int i = 0; i < loops; i++)
            {
                result = Run(inputInstance);
            }
            return result;
        }

        [Benchmark]
        public decimal RunInLoop_Pass_By_Reference()
        {
            decimal result = 0M;
            for (int i = 0; i < loops; i++)
            {
                result = RunIn(in inputInstance);
            }
            return result;
        }

        public decimal Run(Input input)
        {
            return input.Number1;
        }

        public decimal RunIn(in Input input)
        {
            return input.Number1;
        }
    }
}

static void Main(string[] args)
{
    var summary = BenchmarkRunner.Run<InBenchmarking>();

                      Method |      Mean |    Error |   StdDev | Scaled | Allocated |
---------------------------- |----------:|---------:|---------:|-------:|----------:|
 RunNormalLoop_Pass_By_Value | 280.04 ms | 2.219 ms | 1.733 ms |   1.00 |       0 B |
 RunInLoop_Pass_By_Reference |  91.75 ms | 1.733 ms | 1.780 ms |   0.33 |       0 B |

    public static class Factorial
    {
        public static int Calculate(in this int num)
        {
            int result = 1;
            for (int i = num; i > 1; i--)
                result *= i;

            return result;
        }
    }

int num = 3;
Console.WriteLine($"(in num) -> {Factorial.Calculate(in num)}");
Console.WriteLine($"(num) -> {Factorial.Calculate(num)}");
Console.WriteLine($"num. -> {num.Calculate()}");

(in num) -> 6
(num) -> 6
num. -> 6

    public class CX
    {
        public void A(Input a)
        {
            Console.WriteLine("int a");
        }

        public void A(in Input a)
        {
            Console.WriteLine("in int a");
        }
    }

    public class Y
    {
        public void Test()
        {
            var inputInstance = new Input();
            var cx = new CX();
            cx.A(inputInstance); // The call is ambiguous between the following methods or properties: 'CX.A(Input)' and 'CX.A(in Input)'
        }
    }

public IEnumerable<int> B(in int a) // Iterators cannot have ref or out parameters
{
   Console.WriteLine("in int a");
   yield return 1;
}

public async Task C(in int a) // Async methods cannot have ref or out parameters
{
   await Task.Delay(1000);
}

using System;

namespace CS72Tests
{
    struct MyStruct
    {
        public int MyValue { get; set; }

        public void UpdateMyValue(int value)
        {
            MyValue = value;
        }
    }

    public static class TestInStructs
    {
        public static void Run()
        {
            var myStruct = new MyStruct();
            myStruct.UpdateMyValue(1);

            UpdateMyValue(myStruct);

            Console.WriteLine(myStruct.MyValue);
        }

        static void UpdateMyValue(in MyStruct myStruct)
        {
            myStruct.UpdateMyValue(5);
        }
    }
}

static void UpdateMyValue(in MyStruct myStruct)
{
   myStruct.MyValue = 5; // Cannot assign to a member of variable 'in MyStruct' because it is a readonly variable
   myStruct.UpdateMyValue(5);
}

We are excited to announce the release of .NET Core 1.0, ASP.NET Core 1.0 and Entity Framework 1.0, available on Windows, OS X and Linux! .NET Core is a cross-platform, open source, and modular .NET platform for creating modern web apps, microservices, libraries and console applications.

This release includes the .NET Core runtime, libraries and tools and the ASP.NET Core libraries. We are also releasing Visual Studio and Visual Studio Code extensions that enable you to create .NET Core projects. You can get started at https://dot.net/core. Read the release notes for detailed release information. 

DotSpatial is a geographic information system library written for .NET Framework. It allows developers to incorporate spatial data, analysis and mapping functionality into their applications or to contribute GIS extensions to the community.

DotSpatial provides a map control for .NET and several GIS capabilities including:

• Display a map in a .NET Windows Forms.
• Open shapefiles, grids, rasters and images.
• Render symbology and labels.
• Reproject on the fly.
• Manipulate and display attribute data.
• Scientific analysis.
• Read GPS data. 

TL;DR: .NET 7 is fast. Really fast. A thousand performance-impacting PRs went into runtime and core libraries this release, never mind all the improvements in ASP.NET Core and Windows Forms and Entity Framework and beyond. It’s the fastest .NET ever. If your manager asks you why your project should upgrade to .NET 7, you can say “in addition to all the new functionality in the release, .NET 7 is super fast.” 

A Tour of Go (golang) for the C# Developer

Learning other programming languages enhances our work in our primary language. From the perspective of a C# developer, the Go language (golang) has many interesting ideas. Go is opinionated on some things (such as where curly braces go and what items are capitalized). Declaring an unused variable causes a compile failure; the use of "blank identifiers" (or "discards" in C#) are common. Concurrency is baked right in to the language through goroutines and channels. Programming by exception is discouraged; it's actually called a "panic" in Go. Instead, errors are treated as states to be handled like any other data state. We'll explore these features (and others) by building an application that uses concurrent operations to get data from a service. These ideas make us think about the way we program and how we can improve our day-to-day work (in C# or elsewhere).

0:00 Welcome to Go
2:40 Step 1: Basics
12:20 Step 2: Calling a web service
23:35 Step 3: Parsing JSON
36:26 Step 4: "for" loops
41:00 Step 5: Interfaces and methods
50:05 Step 6: Time and Args
55:10 Step 7: Concurrency
1:07:10 Step 8: Errors
1:14:40 Step 9: Concurrency and errors
1:24:35 Where to go next 

• Updated the version of .NET that the debugger uses for running its own C# code to .NET 5 

10 Essential GitHub Repos For Software Developers
Amazing coding resources, free courses, interview preparation, programming best practices, and more 

These are the customer-reported issues addressed in 15.7.3:

• VS2017 compiler creates broken debug build using Qt framework and generates 'Invalid address specified to RtlValidateHeap' error.
• Incorrect code generation for matrix multiplication.
• VS 2017 Update 7: Git History Codelens only showing entries for the past 6 months.
• UWP projects reference multiple NetStandard 2.0 dlls after 15.7.1 upgrade.
• Building C++ code in VS 15.7 with /std:c++17 breaks binary compatibility for std::_Ptr_move_cat.
• Visual Studio 15.7 stuck when opening XAML files.
• CMake configuration fails and generates message "C++ IntelliSense information may be out of date, generate the CMake cache to refresh".
• Unable to start second process for debugging.
• After update to Visual Studio 15.7.1, some test programs fail in start-up due to reading access violation.
• Missing compiler required member 'Microsoft.CSharp.RuntimeBinder.Binder.Convert'.
• Build fails after 15.7.0 update on older project using .NET 3.5 .
• Coloring, typing, tooltips and IntelliSense slow in F# in VS2017 editor.
• F# editing experience takes up to a minute for tooltips and dropdowns to display.
• Certain class member variable value are incorrectly read as zero.
• Attempt to open XAML file for the first time causes VS to sit with the "Opening the file ..." message for about 10 minutes before XAML file opens.
• Visual Studio slows down and freezes, creating work loss.
• The target "GetBuiltProjectOutputRecursive" does not exist in the project.
• Internal error with lambda C++17 after 15.7.1 update.
• UWP App is slow to return a stopped state in IDE.
• MSVC auto-vectorization produces incorrect code or incorrect results.
• Visual Studio closed debug a new instance project1, when a new debug new instance project2 has started.
• Latest update breaks "start without debugging" on multiple projects.
• UWP XAML is very very slow on open.
• XAML viewer freezes on 15.7.2 and 15.8.0 preview 1.1.
• Xamarin UI Test App project template missing.
• Xamarin project creation problem.
• Visual Studio crashes when creating new Mobile APP Xamarin.
• Unable to create Xamarin.Forms-Projects.
• Não consigo criar novos projetos Xamarin Forms - Can't create new projects Xamarin Forms.
• Blank project crash after update.