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‎.gitignore‎

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@@ -49,6 +49,7 @@ ehthumbs_vista.db
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[Bb]in/
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[Oo]bj/
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*.sln
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*.slnx
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*.user
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# Ionide folder, used in F# for VSCode

‎docs/csharp/toc.yml‎

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href: whats-new/version-update-considerations.md
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- name: Tutorials
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items:
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- name: Explore compound assignment
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href: whats-new/tutorials/compound-assignment-operators.md
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- name: Explore primary constructors
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href: whats-new/tutorials/primary-constructors.md
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- name: Explore static interface members

‎docs/csharp/whats-new/tutorials/compound-assignment-operators.md‎

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---
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title: Explore instance compound assignment operators
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description: "C# 14 enables instance compound assignment operators. These can provide better performance by minimizing allocations or copy operations. Learn how to create these operators."
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author: billwagner
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ms.author: wiwagn
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ms.service: dotnet-csharp
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ms.topic: tutorial
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ms.date: 09/15/2025
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#customer intent: As a C# developer, I want implement compound assignment operators so that my algorithms are more efficient.
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---
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# Tutorial: Create compound assignment operators
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[Introduce and explain the purpose of the article.]
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<!-- Required: Introductory paragraphs (no heading)
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Write a brief introduction that can help the user
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decide whether the article is relevant for them and
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to describe how reading the article might benefit
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them.
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-->
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In this tutorial, you:
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> [!div class="checklist"]
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> * Install prerequisites
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> * Analyze the starting sample
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> * Implement compound assignment operators
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> * Analyze completed sample
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## Prerequisites
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- The .NET 10 preview SDK. Download it from the [.NET download site](https://dotnet.microsoft.com/download/dotnet/10.0).
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- Visual Studio 2026 (preview). Download it from the [Visual Studio insiders page](https://visualstudio.microsoft.com/insiders/).
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## Analyze the starting sample
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- Run the app: understand what it does.
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- Read the `GateAttendance` class closely. Note that the operators allocate new instances of objects.
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- (optional) Run the Visual Studio performance profiler to count allocations (134 `GateAttendance` allocations)
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## Implement compound assignment operators
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## Analyze finished sample
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- (Optional) Run the profiler again. Now, only 10 instance of GateAttendance objects are allocated.
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- Try and spot any additional allocations by replacing `+` operations with `+=` where possible.
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- Discuss other options, like `struct` types. Point out that compound assignment helps here by avoiding copy operations
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## Related content
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- What's new.
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- Operators in language reference
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- [Analyze memory usage by using the .NET Object Allocation tool - Visual Studio](~/visualstudio/profiling/dotnet-alloc-tool.md)

‎docs/csharp/whats-new/tutorials/snippets/CompoundAssignment/CompoundAssignment.csproj‎

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<Project Sdk="Microsoft.NET.Sdk">
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<PropertyGroup>
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<OutputType>Exe</OutputType>
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<TargetFramework>net10.0</TargetFramework>
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<ImplicitUsings>enable</ImplicitUsings>
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<Nullable>enable</Nullable>
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<LangVersion>preview</LangVersion>
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</PropertyGroup>
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</Project>

‎docs/csharp/whats-new/tutorials/snippets/CompoundAssignment/GateAttendance.cs‎

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public record class GateAttendance(string GateId)
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{
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private int count = 0;
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public int Count => count;
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public static GateAttendance operator ++(GateAttendance gate)
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{
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GateAttendance updateGate = gate with { count = gate.count + 1 };
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return updateGate;
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}
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public static GateAttendance operator +(GateAttendance gate, int partySize)
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{
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GateAttendance updateGate = gate with { count = gate.count + partySize };
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return updateGate;
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}
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// New style:
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public void operator ++() => this.count++;
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public void operator +=(int partySize) => this.count += partySize;
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}
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‎docs/csharp/whats-new/tutorials/snippets/CompoundAssignment/GateAttendanceTests.cs‎

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public static class TheaterConcertSimulationCompound
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{
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private const int MAX_ATTENDANCE = 1000;
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private const int EXPECTED_SALES = 850;
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public static void SimulateConcertAttendance()
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{
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Console.WriteLine("=== Royal Theater Concert Attendance Simulation ===");
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Console.WriteLine($"Venue Capacity: {MAX_ATTENDANCE} | Expected Sales: {EXPECTED_SALES}");
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Console.WriteLine("Concert: 'Symphony Under the Stars' - 7:30 PM\n");
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// Initialize theater gates
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var theaterGates = new TheaterGates();
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Console.WriteLine("--- Gate Status Before Concert ---");
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PrintTheaterStatus(theaterGates);
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// Simulate pre-concert arrival patterns
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SimulatePreConcertArrivals(theaterGates);
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Console.WriteLine("\n--- Gate Status After Pre-Concert Arrivals (6:30 PM) ---");
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PrintTheaterStatus(theaterGates);
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// Simulate main arrival rush
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SimulateMainArrivalRush(theaterGates);
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Console.WriteLine("\n--- Gate Status After Main Rush (7:15 PM) ---");
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PrintTheaterStatus(theaterGates);
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// Simulate late arrivals
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SimulateLateArrivals(theaterGates);
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Console.WriteLine("\n--- Final Attendance Report (7:30 PM - Concert Start) ---");
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GenerateFinalReport(theaterGates);
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}
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private static void SimulatePreConcertArrivals(TheaterGates gates)
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{
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Console.WriteLine("--- Pre-Concert Arrivals (6:00 PM - 6:30 PM) ---");
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Console.WriteLine("Early patrons and season ticket holders arriving...\n");
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// Early arrivals - mainly main floor, some balcony
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// Main floor gates - moderate traffic
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++gates.MainFloorGates[0]; // Single patron
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gates.MainFloorGates[0] += 2; // Couple
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gates.MainFloorGates[0] += 6; // Corporate early group
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gates.MainFloorGates[1] = gates.MainFloorGates[1] + 4; // Family
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gates.MainFloorGates[1] += 8; // Season ticket holders
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++gates.MainFloorGates[2]; // Single patron
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gates.MainFloorGates[2] += 5; // Early dinner group
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gates.MainFloorGates[3] += 3; // Small group
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gates.MainFloorGates[3] += 7; // VIP early access
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++gates.MainFloorGates[3]; // Individual VIP
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// Balcony gates - lighter but increased traffic
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++gates.BalconyGates[0]; // Single patron
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gates.BalconyGates[0] += 4; // Early bird group
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gates.BalconyGates[1] += 2; // Couple
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gates.BalconyGates[1] += 6; // Student group with early tickets
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++gates.BalconyGates[1]; // Individual student
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Console.WriteLine("Early arrivals processed through all gates.");
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}
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private static void SimulateMainArrivalRush(TheaterGates gates)
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{
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Console.WriteLine("\n--- Main Arrival Rush (6:30 PM - 7:15 PM) ---");
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Console.WriteLine("Peak arrival time - all gates busy...\n");
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var random = new Random();
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// Heavy traffic through main floor gates
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for (int i = 0; i < 3; i++)
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{
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// Gate 1 - busiest entrance (target: ~100-130 people)
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gates.MainFloorGates[0] += random.Next(8, 15); // Corporate group
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++gates.MainFloorGates[0]; // Single patron
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gates.MainFloorGates[0] += random.Next(20, 30); // Tour/large group arrival
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gates.MainFloorGates[0] += random.Next(5, 12); // Family groups
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++gates.MainFloorGates[0]; // Solo attendee
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// Gate 2 - second busiest (target: ~85-115 people)
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gates.MainFloorGates[1] = gates.MainFloorGates[1] + random.Next(6, 12); // Group booking
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++gates.MainFloorGates[1]; // Single patron
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gates.MainFloorGates[1] += random.Next(18, 28); // Large family/reunion
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gates.MainFloorGates[1] += random.Next(8, 15); // Corporate/business group
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gates.MainFloorGates[1] += random.Next(4, 8); // Couples/small groups
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++gates.MainFloorGates[1]; // Individual patron
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// Gate 3 - moderate traffic (target: ~70-95 people)
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++gates.MainFloorGates[2]; // Individual
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gates.MainFloorGates[2] += random.Next(4, 8); // Small group
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gates.MainFloorGates[2] += random.Next(15, 22); // Community/organization group
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gates.MainFloorGates[2] += random.Next(10, 16); // Club/society members
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++gates.MainFloorGates[2]; // Solo attendee
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gates.MainFloorGates[2] += random.Next(6, 12); // Friends/social group
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// Gate 4 - lighter but steady (target: ~60-85 people)
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gates.MainFloorGates[3] += random.Next(3, 6); // Family group
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gates.MainFloorGates[3] += random.Next(8, 15); // Celebration/event group
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++gates.MainFloorGates[3]; // Individual attendee
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gates.MainFloorGates[3] += random.Next(5, 10); // Couples/pairs
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// Balcony gates - steady increased flow
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// Left balcony gate (target: ~80-100 people)
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++gates.BalconyGates[0]; // Single patron
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gates.BalconyGates[0] += random.Next(5, 10); // Small group
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gates.BalconyGates[0] += random.Next(15, 25); // Student/educational group
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gates.BalconyGates[0] += random.Next(10, 18); // Budget-conscious attendees
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++gates.BalconyGates[0]; // Individual
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gates.BalconyGates[0] += random.Next(6, 12); // Senior/community group
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// Right balcony gate (target: ~70-95 people)
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gates.BalconyGates[1] += random.Next(4, 8); // Small group
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++gates.BalconyGates[1]; // Individual
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gates.BalconyGates[1] += random.Next(16, 24); // Academic/institutional group
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gates.BalconyGates[1] += random.Next(10, 16); // Community organization
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gates.BalconyGates[1] += random.Next(4, 8); // Young professionals/friends
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++gates.BalconyGates[1]; // Solo patron
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}
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Console.WriteLine("Peak rush period completed - all gates processed heavy traffic.");
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}
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private static void SimulateLateArrivals(TheaterGates gates)
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{
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Console.WriteLine("\n--- Late Arrivals (7:15 PM - 7:30 PM) ---");
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Console.WriteLine("Final patrons arriving before curtain...\n");
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var random = new Random();
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// Light but varied traffic as concert approaches
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// Main floor gates - scattered late arrivals (1-8 people per gate)
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++gates.MainFloorGates[0]; // Last-minute arrival
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gates.MainFloorGates[0] += random.Next(2, 6); // Delayed group
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gates.MainFloorGates[1] += random.Next(1, 4); // Rushing small group
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gates.MainFloorGates[1] += random.Next(2, 7); // Traffic/parking delayed group
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++gates.MainFloorGates[2]; // Single late arrival
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gates.MainFloorGates[2] += random.Next(1, 5); // Delayed couple/small group
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gates.MainFloorGates[3] += random.Next(1, 4); // Late couple
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gates.MainFloorGates[3] += random.Next(2, 6); // Last-minute purchasers
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++gates.MainFloorGates[3]; // Solo rush arrival
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// Balcony gates - lighter late traffic (1-5 people per gate)
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++gates.BalconyGates[0]; // Late balcony patron
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gates.BalconyGates[0] += random.Next(1, 4); // Delayed small group
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gates.BalconyGates[1] += random.Next(1, 3); // Final arrivals
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gates.BalconyGates[1] += random.Next(2, 5); // Work-delayed group
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++gates.BalconyGates[1]; // Individual latecomer
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Console.WriteLine("Final arrivals processed - concert about to begin!");
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}
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private static void PrintTheaterStatus(TheaterGates gates)
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{
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Console.WriteLine("Main Floor Gates:");
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for (int i = 0; i < gates.MainFloorGates.Length; i++)
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{
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var gate = gates.MainFloorGates[i];
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Console.WriteLine($" {gate.GateId}: {gate.Count,3} attendees");
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}
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var mainFloorTotal = gates.MainFloorGates.Sum(g => g.Count);
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Console.WriteLine($" Main Floor Subtotal: {mainFloorTotal,3} attendees");
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Console.WriteLine("\nBalcony Gates:");
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for (int i = 0; i < gates.BalconyGates.Length; i++)
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{
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var gate = gates.BalconyGates[i];
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Console.WriteLine($" {gate.GateId}: {gate.Count,3} attendees");
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}
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var balconyTotal = gates.BalconyGates.Sum(g => g.Count);
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Console.WriteLine($" Balcony Subtotal: {balconyTotal,3} attendees");
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var totalAttendance = mainFloorTotal + balconyTotal;
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Console.WriteLine($"\nTotal Current Attendance: {totalAttendance,3} / {MAX_ATTENDANCE}");
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}
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private static void GenerateFinalReport(TheaterGates gates)
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{
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var mainFloorTotal = gates.MainFloorGates.Sum(g => g.Count);
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var balconyTotal = gates.BalconyGates.Sum(g => g.Count);
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var totalAttendance = mainFloorTotal + balconyTotal;
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PrintTheaterStatus(gates);
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Console.WriteLine("\n" + new string('=', 50));
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Console.WriteLine("FINAL CONCERT ATTENDANCE REPORT");
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Console.WriteLine(new string('=', 50));
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Console.WriteLine($"Expected Sales: {EXPECTED_SALES,3}");
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Console.WriteLine($"Actual Attendance: {totalAttendance,3}");
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Console.WriteLine($"Venue Capacity: {MAX_ATTENDANCE,3}");
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var attendanceRate = (double)totalAttendance / EXPECTED_SALES * 100;
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var capacityUtilization = (double)totalAttendance / MAX_ATTENDANCE * 100;
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Console.WriteLine($"Attendance Rate: {attendanceRate,5:F1}% of expected");
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Console.WriteLine($"Capacity Utilization: {capacityUtilization,5:F1}% of maximum");
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// Gate distribution analysis
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Console.WriteLine($"\nGate Distribution:");
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Console.WriteLine($"Main Floor: {mainFloorTotal,3} ({(double)mainFloorTotal/totalAttendance*100:F1}%)");
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Console.WriteLine($"Balcony: {balconyTotal,3} ({(double)balconyTotal/totalAttendance*100:F1}%)");
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// Performance indicators using switch expression
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var performanceMessage = totalAttendance switch
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{
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var t when t >= EXPECTED_SALES * 0.95 => "\n✅ Excellent attendance! Concert exceeded expectations.",
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var t when t >= EXPECTED_SALES * 0.85 => "\n✅ Good attendance! Concert met expectations.",
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var t when t >= EXPECTED_SALES * 0.70 => "\n⚠️ Moderate attendance. Consider marketing review.",
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_ => "\n❌ Low attendance. Significant marketing review needed."
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};
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Console.WriteLine(performanceMessage);
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Console.WriteLine("\nConcert begins! 🎼");
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}
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}
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public struct TheaterGates
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{
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// Main floor gates (4 gates) - initialized with default gate instances
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public GateAttendance[] MainFloorGates { get; set; } =
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[
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new GateAttendance("Main-Floor-Gate-1"),
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new GateAttendance("Main-Floor-Gate-2"),
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new GateAttendance("Main-Floor-Gate-3"),
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new GateAttendance("Main-Floor-Gate-4")
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];
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// Balcony gates (2 gates) - initialized with default gate instances
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public GateAttendance[] BalconyGates { get; set; } =
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[
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new GateAttendance("Balcony-Gate-Left"),
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new GateAttendance("Balcony-Gate-Right")
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];
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// Explicit constructor required when using field initializers in structs
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public TheaterGates()
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{
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}
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}

‎docs/csharp/whats-new/tutorials/snippets/CompoundAssignment/Program.cs‎

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TheaterConcertSimulationCompound.SimulateConcertAttendance();
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