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C# Coding Standards for .NET

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1. Introduction
This document describes rules and recommendations for developing applications and class libraries using the C#
Language. The goal is to define guidelines to enforce consistent style and formatting and help developers avoid common
pitfalls and mistakes.
Specifically, this document covers Naming Conventions, Coding Style, Language Usage, and Object Model Design.
1.1 Scope
This document only applies to the C# Language and the .NET Framework Common Type System(CTS) it implements.
Although the C# language is implemented alongside the .NET Framework, this document does not address usage of
.NET Framework class libraries. However, common patterns and problems related to C#’s usage of the .NET Framework
are addressed in a limited fashion.
Even though standards for curly-braces ({ or }) and white space(tabs vs. spaces) are always controversial, these topics
are addressed here to ensure greater consistency and maintainability of source code.
1.2 Document Conventions
Much like the ensuing coding standards, this document requires standards in order to ensure clarity when stating the rules
and guidelines. Certain conventions are used throughout this document to add emphasis.
Below are some of the common conventions used throughout this document.
Coloring & Emphasis:
Blue Text colored blue indicates a C# keyword or .NET type.
Bold Text with additional emphasis to make it stand-out.
Always Emphasizes this rule must be enforced.
Never Emphasizes this action must not happen.
Do Not Emphasizes this action must not happen.
Avoid Emphasizes that the action should be prevented, but
some exceptions may exist.
Try Emphasizes that the rule should be attempted whenever possible and appropriate.
Example Precedes text used to illustrate a rule or recommendation.
Reason Explains the thoughts and purpose behind a rule or recommendation.
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1.3 Terminology & Definitions
The following terminology is referenced throughout this document:
Access Modifier
C# keywords public, protected, internal, and private declare the allowed code-accessibility of types
and their members. Although default access modifiers vary, classes and most other members use the default
of private. Notable exceptions are interfaces and enums which both default to public.
Camel Case
A word with the first letter lowercase, and the first letter of each subsequent word-part capitalized.
Example: customerName
Common Type System
The .NET Framework common type system (CTS) defines how types are declared, used, and managed. All
native C# types are based upon the CTS to ensure support for cross-language integration.
A developer defined token used to uniquely name a declared object or object instance.
Example: public class MyClassNameIdentifier { … }
Magic Number
Any numeric literal used within an expression (or to initialize a variable) that does not have an obvious or wellknown
meaning. This usually excludes the integers 0 or 1 and any other numeric equivalent precision that
evaluates as zero.
Pascal Case
A word with the first letter capitalized, and the first letter of each subsequent word-part capitalized.
Example: CustomerName
Premature Generalization
As it applies to object model design; this is the act of creating abstractions within an object model not based
upon concrete requirements or a known future need for the abstraction. In simplest terms: “Abstraction for
the sake of Abstraction.”
1.4 Flags
The following flags are used to help clarify or categorize certain statements:
[C#v2+]A flag to identify rules and statements that apply only to C# Language Specification v2.0 or greater.
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Quick Summary
This section contains tables describing a high-level summary of the major standards covered in this document. These
tables are not comprehensive, but give a quick glance at commonly referenced elements.
1.4.1 Naming Conventions
“c” = camelCase
“P” = PascalCase
“_” = Prefix with _Underscore
“x” = Not Applicable.
Identifier          Public       Protected   Internal    Private           Notes
Project File         P                   x                       x              x                     Match Assembly & Namespace.
Source File         P                   x                        x              x                      Match contained class.
Other Files          P                   x                        x             x                      Apply where possible.
Namespace        P                   x                        x              x                      Partial Project/Assembly match.
Class or Struct  P                   P                        P             P                       Add suffix of subclass.
Interface             P                   P                        P             P                       Prefix with a capital I.
Generic Class    P                   P                         P            P                       Use T or K as Type identifier.
Method               P                   P                         P             P                       Use a Verb or Verb-Object pair.
Property            P                    P                        P             P                      Do not prefix with Get or Set.
Field                    P                    P                         P             _c                   Only use Private fields.No Hungarian Notation!
Constant            P                    P                         P             _c
Static Field       P                    P                         P              _c                   Only use Private fields.
Enum                  P                    P                         P             P                      Options are also PascalCase.
Delegate            P                    P                         P             P
Event                  P                   P                          P             P
Inline Variable x                  x                        x              c                          Avoid single-character and enumerated
Parameter        x                    x                         x               c
1.4.2 Coding Style
Code Style
Source Files                        One Namespace per file and one class per file.
Curly Braces                       On new line. Always use braces when optional.
Indention                            Use tabs with size of 4.
Comments                            Use     // or /// but not /* … */ and do not flowerbox.
Variables                              One variable per declaration.
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1.4.3 Language Usage
Code Style
Native Data Types                         Use built-in C# native data types vs .NET CTS types.
(Use int NOT Int32)
Enums                                                 Avoid changing default type.
Generics [C#v2+]                         Prefer Generic Types over standard or strong-typed classes.
Properties                                           Never prefix with Get or Set.
Methods                                               Use a maximum of 7 parameters.
base and this                                     Use only in constructors or within an override.
Ternary conditions                     Avoid complex conditions.
foreach statements                     Do not modify enumerated items within a foreach statement.
                                                                    Avoid evaluating Boolean conditions against true or false.
No embedded assignment.
Avoid embedded method invocation.
Exceptions                                      Do not use exceptions for flow control.
Use throw; not throw e; when re-throwing.
Only catch what you can handle.
Use validation to avoid exceptions.
Derive from Execption not ApplicationException.
Events                                                    Always check for null before invoking.
Locking                                              Use lock() not Monitor.Enter().
Do not lock on an object type or “this”.
Do lock on private objects.
Dispose() & Close()                    Always invoke them if offered, declare where needed.
Finalizers                                            Avoid.
Use the C# Destructors.
Do not create Finalize() method.
AssemblyVersion                          Increment manually.
ComVisibleAttribute                  Set to false for all assemblies.

2. Naming Conventions
Consistency is the key to maintainable code. This statement is most true for naming your projects, source files, and
identifiers including Fields, Variables, Properties, Methods, Parameters, Classes, Interfaces, and Namespaces.
2.1 General Guidelines
1. Always use Camel Case or Pascal Case names.
2. Avoid ALL CAPS and all lowercase names. Single lowercase words or letters are acceptable.
3. Do not create declarations of the same type (namespace, class, method, property, field, or parameter) and
access modifier (protected, public, private, internal) that vary only by capitalization.
4. Do not use names that begin with a numeric character.
5. Do add numeric suffixes to identifier names.
6. Always choose meaningful and specific names.
7. Always err on the side of verbosity not terseness.
8. Variables and Properties should describe an entity not the type or size.
9. Do not use Hungarian Notation!
Example: strName or iCount
10. Avoid using abbreviations unless the full name is excessive.
11. Avoid abbreviations longer than 5 characters.
12. Any Abbreviations must be widely known and accepted.
13. Use uppercase for two-letter abbreviations, and Pascal Case for longer abbreviations.
14. Do not use C# reserved words as names.
15. Avoid naming conflicts with existing .NET Framework namespaces, or types.
16. Avoid adding redundant or meaningless prefixes and suffixes to identifiers
// Bad!
public enum ColorsEnum {…}
public class CVehicle {…}
public struct RectangleStruct {…}
17. Do not include the parent class name within a property name.
Example: Customer.Name NOT Customer.CustomerName
18. Try to prefix Boolean variables and properties with “Can”, “Is” or “Has”.
19. Append computational qualifiers to variable names like Average, Count, Sum, Min, and Max where
20. When defining a root namespace, use a Product, Company, or Developer Name as the root. Example:

2.2 Name Usage & Syntax
Identifier                                                   Naming Convention
Project File                                                      Pascal Case.
Always match Assembly Name & Root Namespace.
LanceHunt.Web.csproj -> LanceHunt.Web.dll -> namespace
 Source File                                                    Pascal Case.
Always match Class name and file name.
Avoid including more than one Class, Enum (global), or Delegate (global) per file.                                                                                                                                                                                              descriptive file name when  containing multiple Class, Enum, or Delegates.

MyClass.cs => public class MyClass
Embedded File
Try to use Pascal Case.
Use a name describing the file contents.
Namespace Pascal Case.
Try to partially match Project/Assembly Name.
namespace LanceHunt.Web
Class or Struct Pascal Case.
Use a noun or noun phrase for class name.
Add an appropriate class-suffix when sub-classing another type when possible.
private class MyClass
internal class SpecializedAttribute : Attribute
public class CustomerCollection : CollectionBase
public class CustomEventArgs : EventArgs
private struct ApplicationSettings
Interface Pascal Case.
Always prefix interface name with capital “I”.
interface ICustomer
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Generic Class
Parameter Type
Always use a single capital letter, such as T or K.
public class FifoStack<T>
public void Push(<T> obj)
public <T> Pop()
Method Pascal Case.
Try to use a Verb or Verb-Object pair.
public void Execute() {…}
private string GetAssemblyVersion(Assembly target) {…}
Property Pascal Case.
Property name should represent the entity it returns. Never prefix property names with
“Get” or “Set”.
public string Name
(Public, Protected,
or Internal)
Pascal Case.
Avoid using non-private Fields!
Use Properties instead.
public string Name;
protected IList InnerList;
Field (Private) Camel Case and prefix with a single underscore (_) character.
private string _name;
Constant or
Static Field
Treat like a Field.
Choose appropriate Field access-modifier above.
Enum Pascal Case (both the Type and the Options).
Add the FlagsAttribute to bit-mask multiple options.
public enum CustomerTypes

Delegate or Event Treat as a Field.
Choose appropriate Field access-modifier above.
public event EventHandler LoadPlugin;
Variable (inline) Camel Case.
Avoid using single characters like “x” or “y” except in FOR loops.
Avoid enumerating variable names like text1, text2, text3 etc.
Parameter Camel Case.
public void Execute(string commandText, int iterations)
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3. Coding Style
Coding style causes the most inconsistency and controversy between developers. Each developer has a preference, and
rarely are two the same. However, consistent layout, format, and organization are key to creating maintainable code.
The following sections describe the preferred way to implement C# source code in order to create readable, clear, and
consistent code that is easy to understand and maintain.
3.1 Formatting
1. Never declare more than 1 namespace per file.
2. Avoid putting multiple classes in a single file.
3. Always place curly braces ({ and }) on a new line.
4. Always use curly braces ({ and }) in conditional statements.
5. Always use a Tab & Indention size of 4.
6. Declare each variable independently – not in the same statement.
7. Place namespace “using” statements together at the top of file. Group .NET namespaces above custom
8. Group internal class implementation by type in the following order:
a. Member variables.
b. Constructors & Finalizers.
c. Nested Enums, Structs, and Classes.
d. Properties
e. Methods
9. Sequence declarations within type groups based upon access modifier and visibility:
a. Public
b. Protected
c. Internal
d. Private
10. Segregate interface Implementation by using #region statements.
11. Append folder-name to namespace for source files within sub-folders.
12. Recursively indent all code blocks contained within braces.
13. Use white space (CR/LF, Tabs, etc) liberally to separate and organize code.
14. Only declare related attribute declarations on a single line, otherwise stack each attribute as a separate
// Bad!
[Attrbute1, Attrbute2, Attrbute3]
public class MyClass
// Good!
[Attrbute1, RelatedAttribute2]
public class MyClass
15. Place Assembly scope attribute declarations on a separate line.
16. Place Type scope attribute declarations on a separate line.
17. Place Method scope attribute declarations on a separate line.
18. Place Member scope attribute declarations on a separate line.
19. Place Parameter attribute declarations inline with the parameter.
20. If in doubt, always err on the side of clarity and consistency.
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3.2 Code Commenting
21. All comments should be written in the same language, be grammatically correct, and contain appropriate
22. Use // or /// but never /* … */
23. Do not “flowerbox” comment blocks.
// ***************************************
// Comment block
// ***************************************
24. Use inline-comments to explain assumptions, known issues, and algorithm insights.
25. Do not use inline-comments to explain obvious code. Well written code is self documenting.
26. Only use comments for bad code to say “fix this code” – otherwise remove, or rewrite the code!
27. Include comments using Task-List keyword flags to allow comment-filtering.
// TODO: Place Database Code Here
// UNDONE: Removed P\Invoke Call due to errors
// HACK: Temporary fix until able to refactor
28. Always apply C# comment-blocks (///) to public, protected, and internal declarations.
29. Only use C# comment-blocks for documenting the API.
30. Always include <summary> comments. Include <param>, <return>, and <exception> comment
sections where applicable.
31. Include <see cref=””/> and <seeAlso cref=””/> where possible.
32. Always add CDATA tags to comments containing code and other embedded markup in order to avoid
encoding issues.
/// <example>
/// Add the following key to the “appSettings” section of your config:
/// <code><![CDATA[
/// <configuration>
/// <appSettings>
/// <add key=”mySetting” value=”myValue”/>
/// </appSettings>
/// </configuration>
/// ]]></code>
/// </example>
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4. Language Usage
4.1 General
1. Do not omit access modifiers. Explicitly declare all identifiers with the appropriate access modifier instead of
allowing the default.
// Bad!
Void WriteEvent(string message)
// Good!
private Void WriteEvent(string message)
2. Do not use the default (“1.0.*”) versioning scheme. Increment the AssemblyVersionAttribute value
3. Set the ComVisibleAttribute to false for all assemblies.
4. Only selectively enable the ComVisibleAttribute for individual classes when needed.
[assembly: ComVisible(false)]
public MyClass
5. Consider factoring classes containing unsafe code blocks into a separate assembly.
6. Avoid mutual references between assemblies.
4.2 Variables & Types
7. Try to initialize variables where you declare them.
8. Always choose the simplest data type, list, or object required.
9. Always use the built-in C# data type aliases, not the .NET common type system (CTS).
short NOT System.Int16
int NOT System.Int32
long NOT System.Int64
string NOT System.String
10. Only declare member variables as private. Use properties to provide access to them with public,
protected, or internal access modifiers.
11. Try to use int for any non-fractional numeric values that will fit the int datatype – even variables for nonnegative
12. Only use long for variables potentially containing values too large for an int.
13. Try to use double for fractional numbers to ensure decimal precision in calculations.
14. Only use float for fractional numbers that will not fit double or decimal.
15. Avoid using float unless you fully understand the implications upon any calculations.
16. Try to use decimal when fractional numbers must be rounded to a fixed precision for calculations. Typically
this will involve money.
17. Avoid using sbyte, short, uint, and ulong unless it is for interop (P/Invoke) with native libraries.
Lance Hunt C# Coding Standards for .NET
18. Avoid specifying the type for an enum – use the default of int unless you have an explicit need for long (very
19. Avoid using inline numeric literals (magic numbers). Instead, use a Constant or Enum.
20. Avoid declaring string literals inline. Instead use Resources, Constants, Configuration Files, Registry or other
data sources.
21. Declare readonly or static readonly variables instead of constants for complex types.
22. Only declare constants for simple types.
23. Avoid direct casts. Instead, use the “as” operator and check for null.
object dataObject = LoadData();
DataSet ds = dataObject as DataSet;
if(ds != null)
24. Always prefer C# Generic collection types over standard or strong-typed collections. [C#v2+]
25. Always explicitly initialize arrays of reference types using a for loop.
26. Avoid boxing and unboxing value types.
int count = 1;
object refCount = count; // Implicitly boxed.
int newCount = (int)refCount; // Explicitly unboxed.
27. Floating point values should include at least one digit before the decimal place and one after.
Example: totalPercent = 0.05;
28. Try to use the “@” prefix for string literals instead of escaped strings.
29. Prefer String.Format() or StringBuilder over string concatenation.
30. Never concatenate strings inside a loop.
31. Do not compare strings to String.Empty or “” to check for empty strings. Instead, compare by using
String.Length == 0.
32. Avoid hidden string allocations within a loop. Use String.Compare() for case-sensitive
Example: (ToLower() creates a temp string)
Lance Hunt C# Coding Standards for .NET 13
// Bad!
int id = -1;
string name = “lance hunt”;
for(int i=0; i < customerList.Count; i++)
if(customerList[i].Name.ToLower() == name)
id = customerList[i].ID;
// Good!
int id = -1;
string name = “lance hunt”;
for(int i=0; i < customerList.Count; i++)
// The “ignoreCase = true” argument performs a
// case-insensitive compare without new allocation.
if(String.Compare(customerList[i].Name, name, true)== 0)
id = customerList[i].ID;
4.3 Flow Control
33. Avoid invoking methods within a conditional expression.
34. Avoid creating recursive methods. Use loops or nested loops instead.
35. Avoid using foreach to iterate over immutable value-type collections. E.g. String arrays.
36. Do not modify enumerated items within a foreach statement.
37. Use the ternary conditional operator only for trivial conditions. Avoid complex or compound ternary operations.
Example: int result = isValid ? 9 : 4;
38. Avoid evaluating Boolean conditions against true or false.
// Bad!
if (isValid == true)
// Good!
if (isValid)
39. Avoid assignment within conditional statements.
Example: if((i=2)==2) {…}
Lance Hunt C# Coding Standards for .NET
40. Avoid compound conditional expressions – use Boolean variables to split parts into multiple manageable
// Bad!
if (((value > _highScore) && (value != _highScore)) && (value < _maxScore))
// Good!
isHighScore = (value >= _highScore);
isTiedHigh = (value == _highScore);
isValid = (value < _maxValue);
if ((isHighScore && ! isTiedHigh) && isValid)
41. Avoid explicit Boolean tests in conditionals.
// Bad!
if(IsValid == true)
// Good!
42. Only use switch/case statements for simple operations with parallel conditional logic.
43. Prefer nested if/else over switch/case for short conditional sequences and complex conditions.
44. Prefer polymorphism over switch/case to encapsulate and delegate complex operations.
4.4 Exceptions
45. Do not use try/catch blocks for flow-control.
46. Only catch exceptions that you can handle.
47. Never declare an empty catch block.
48. Avoid nesting a try/catch within a catch block.
49. Always catch the most derived exception via exception filters.
50. Order exception filters from most to least derived exception type.
51. Avoid re-throwing an exception. Allow it to bubble-up instead.
52. If re-throwing an exception, preserve the original call stack by omitting the exception argument from the throw
// Bad!
catch(Exception ex)
throw ex;
// Good!
53. Only use the finally block to release resources from a try statement.
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54. Always use validation to avoid exceptions.
// Bad!
Catch(Exception ex)
// handle exception if already closed!
// Good!
if(conn.State != ConnectionState.Closed)
55. Always set the innerException property on thrown exceptions so the exception chain & call stack are
56. Avoid defining custom exception classes. Use existing exception classes instead.
57. When a custom exception is required;
a. Always derive from Exception not ApplicationException.
b. Always suffix exception class names with the word “Exception”.
c. Always add the SerializableAttribute to exception classes.
d. Always implement the standard “Exception Constructor Pattern”:
public MyCustomException ();
public MyCustomException (string message);
public MyCustomException (string message, Exception innerException);
e. Always implement the deserialization constructor:
protected MyCustomException(SerializationInfo info, StreamingContext contxt);
58. Always set the appropriate HResult value on custom exception classes.
(Note: the ApplicationException HResult = -2146232832)
59. When defining custom exception classes that contain additional properties:
a. Always override the Message property, ToString() method and the implicit operator string
to include custom property values.
b. Always modify the deserialization constructor to retrieve custom property values.
c. Always override the GetObjectData(…) method to add custom properties to the serialization collection.
public override void GetObjectData(SerializationInfo info,
StreamingContext context)
base.GetObjectData (info, context);
info.AddValue(“MyValue”, _myValue);
4.5 Events, Delegates, & Threading
60. Always check Event & Delegate instances for null before invoking.
61. Use the default EventHandler and EventArgs for most simple events.
62. Always derive a custom EventArgs class to provide additional data.
63. Use the existing CancelEventArgs class to allow the event subscriber to control events.
64. Always use the “lock” keyword instead of the Monitor type.
65. Only lock on a private or private static object.
Example: lock(myVariable);
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66. Avoid locking on a Type.
Example: lock(typeof(MyClass));
67. Avoid locking on the current object instance.
Example: lock(this);
4.6 Object Composition
68. Always declare types explicitly within a namespace. Do not use the default “{global}” namespace.
69. Avoid overuse of the public access modifier. Typically fewer than 10% of your types and members will be
part of a public API, unless you are writing a class library.
70. Consider using internal or private access modifiers for types and members unless you intend to support
them as part of a public API.
71. Never use the protected access modifier within sealed classes unless overriding a protected member of
an inherited type.
72. Avoid declaring methods with more than 5 parameters. Consider refactoring this code.
73. Try to replace large parameter-sets (> than 5 parameters) with one or more class or struct parameters –
especially when used in multiple method signatures.
74. Do not use the “new” keyword on method and property declarations to hide members of a derived type.
75. Only use the “base” keyword when invoking a base class constructor or base implementation within an
76. Consider using method overloading instead of the params attribute (but be careful not to break CLS
Compliance of your API’s).
77. Always validate an enumeration variable or parameter value before consuming it. They may contain any value
that the underlying Enum type (default int) supports.
public void Test(BookCategory cat)
if (Enum.IsDefined(typeof(BookCategory), cat))
78. Consider overriding Equals() on a struct.
79. Always override the Equality Operator (==) when overriding the Equals() method.
80. Always override the String Implicit Operator when overriding the ToString() method.
81. Always call Close() or Dispose() on classes that offer it.
82. Wrap instantiation of IDisposable objects with a “using” statement to ensure that Dispose() is
automatically called.
using(SqlConnection cn = new SqlConnection(_connectionString))
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83. Always implement the IDisposable interface & pattern on classes referencing external resources.
Example: (shown with optional Finalizer)
public void Dispose()
protected virtual void Dispose(bool disposing)
if (disposing)
// Free other state (managed objects).
// Free your own state (unmanaged objects).
// Set large fields to null.
// C# finalizer. (optional)
// Simply call Dispose(false).
Dispose (false);
84. Avoid implementing a Finalizer.
Never define a Finalize() method as a finalizer. Instead use the C# destructor syntax.
// Good
~MyClass {…}
// Bad
void Finalize(){…}
Lance Hunt C# Coding Standards for .NET
5. Object Model & API Design
1. Always prefer aggregation over inheritance.
2. Avoid “Premature Generalization”. Create abstractions only when the intent is understood.
3. Do the simplest thing that works, then refactor when necessary.
4. Always make object-behavior transparent to API consumers.
5. Avoid unexpected side-affects when properties, methods, and constructors are invoked.
6. Always separate presentation layer from business logic.
7. Always prefer interfaces over abstract classes.
8. Try to include the design-pattern names such as “Bridge”, “Adapter”, or “Factory” as a suffix to class names
where appropriate.
9. Only make members virtual if they are designed and tested for extensibility.
10. Refactor often!


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