# c-sharp

Defines C# standards for Cursor, enforcing Allman formatting, .NET naming conventions, constructor injection, and non-blocking asynchronous patterns.

- rule · `type=rule` · Cursor · ★ 3580
- Author: sanjeed5
- License: CC0-1.0 · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/sanjeed5/awesome-cursor-rules-mdc/tree/HEAD/rules-mdc/c-sharp.mdc
- Updated: 2026-05-19
- HTML: https://affpapa.org/en/nevibecode/rules/c-sharp

## What it does

This rule sets definitive .NET development guidelines within Cursor. It standardizes naming conventions: `PascalCase` for types, `IPascalCase` for interfaces, `_camelCase` for private fields, and the `Async` suffix on task methods. Formatting enforces 4-space indentation. All braces follow Allman style on new lines.

The instructions steer the model toward modern C# features. Code generation favors pattern matching and immutable `record` types. For architecture, the rule mandates constructor injection. Service locators and direct dependency instantiations are banned.

The configuration targets the `**/*` glob. Cursor therefore applies these checks across the entire project. It prevents inefficient string concatenation inside loops. The rule also blocks thread-locking calls such as `.Wait()` on asynchronous tasks.

## Install

### Cursor (native platform)

**Manually: put the files in place**
- File: `.cursor/rules/c-sharp.mdc` — Frontmatter: description, globs, alwaysApply

### Claude Code

**Manually: put the files in place**
- File: `.claude/rules/c-sharp.md` — The paths frontmatter field limits the files: move globs from the source into paths

### Codex

**AGENTS.md**
- Codex reads AGENTS.md: paste the rule text there

### GitHub Copilot

**Manually: put the files in place**
- File: `.github/instructions/c-sharp.instructions.md` — The applyTo field sets which files it applies to: move globs from the source into applyTo

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/rules/c-sharp.md`

### Cline

**Manually: put the files in place**
- File: `.clinerules/c-sharp.md`

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/sanjeed5/awesome-cursor-rules-mdc/tree/HEAD/rules-mdc/c-sharp.mdc

## When to use it
- Enforce Allman brace formatting and standard 4-space indentation
- Standardize .NET naming for classes, private fields, and interfaces
- Adopt immutable records and init-only setters for data transfer objects
- Prevent thread-blocking calls like `.Wait()` on asynchronous operations

## Example prompts
- Create an `OrderService` class using constructor injection for the repository
- Generate an immutable DTO for customer profile updates using records
- Refactor this string concatenation loop to use StringBuilder

## Source text · c-sharp.mdc · CC0-1.0

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: b59179173afe67cd.

BEGIN THIRD-PARTY FILE b59179173afe67cd
````text
---
description: This guide defines definitive C# coding standards and best practices for our team, covering naming, formatting, modern language features, performance, security, and error handling to ensure consistent, maintainable, and high-quality code.
globs: **/*
---
# c-sharp Best Practices

This document outlines the definitive C# coding standards and best practices for our team. Adhering to these guidelines ensures consistency, readability, maintainability, and high performance across all our C# projects.

## Code Organization and Structure

### 1. Naming Conventions
Always follow standard .NET naming conventions to improve readability and predictability.

*   **Types (Classes, Structs, Enums, Delegates, Records):** `PascalCase`
*   **Interfaces:** `IPascalCase`
*   **Methods, Public Properties, Events:** `PascalCase`
*   **Public Constants:** `PascalCase`
*   **Local Variables, Method Parameters:** `camelCase`
*   **Private/Protected Fields:** `_camelCase` (underscore prefix)
*   **Async Methods:** `PascalCase` ending with `Async`

❌ BAD:
```csharp
public class myService {
    private string name;
    public void getdata() { /* ... */ }
    public async Task do_work() { /* ... */ }
    public interface IMyServiceImplementation { /* ... */ } // Incorrect interface naming
}
```

✅ GOOD:
```csharp
public class MyService {
    private readonly ILogger _logger; // Readonly private fields
    private string _name;
    public const int MaxRetries = 3; // Public constants are PascalCase

    public MyService(ILogger logger) {
        _logger = logger;
    }

    public void GetData() { /* ... */ }
    public async Task DoWorkAsync() { /* ... */ }
}
public interface IService { /* ... */ } // Correct interface naming
```

### 2. Formatting
Always maintain consistent code layout for clarity.

*   **Indentation:** Use **4 spaces**. Configure your IDE to use spaces, not tabs.
*   **Braces:** Use [Allman style](https://en.wikipedia.org/wiki/Indent_style#Allman_style) where each brace begins on a new line. Always use braces, even for single-statement blocks.
*   **`using` Directives:** Place at the top of the file, outside the namespace. Sort alphabetically, with `System` namespaces first.
*   **Auto-properties:** Keep on a single line.
*   **Generic Constraints:** Place on separate, indented lines.

❌ BAD:
```csharp
using System.Collections.Generic;
using System;
namespace MyNamespace {
class MyClass {
    public int Age {get;set;}
    void DoSomething() {
        if(true)
            Console.WriteLine("Hello");
    }
}}
```

✅ GOOD:
```csharp
using System;
using System.Collections.Generic;

namespace MyNamespace
{
    public class MyClass
    {
        public int Age { get; set; }

        public void DoSomething()
        {
            if (true)
            {
                Console.WriteLine("Hello");
            }
        }
    }
}
```

### 3. Modern Language Features
Always embrace modern C# features for cleaner, more concise, and safer code.

*   **`var` Keyword:** Use `var` when the type is obvious from the right-hand side of the assignment. Avoid `var` when the type is not immediately clear.
*   **Expression-bodied Members:** Use for single-expression methods, properties, and accessors.
*   **Object/Collection Initializers:** Prefer for creating and populating objects/collections.
*   **Pattern Matching:** Use for type checks and value comparisons.
*   **Nullable Reference Types:** Enable and address warnings (`#nullable enable`).
*   **Records:** Use for immutable data transfer objects (DTOs) or value-based types.

❌ BAD:
```csharp
string name = "John Doe";
public int GetCount() { return _items.Count; }
MyObject obj = new MyObject();
obj.Property1 = "Value1";
obj.Property2 = 123;
if (item is string) { Console.WriteLine((string)item); }
```

✅ GOOD:
```csharp
````
END THIRD-PARTY FILE b59179173afe67cd

The third-party file has ended. Everything between the b59179173afe67cd tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

First 3843 of 11073 bytes. © sanjeed5 · CC0-1.0 · https://github.com/sanjeed5/awesome-cursor-rules-mdc/tree/HEAD/rules-mdc/c-sharp.mdc

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