C# Language
- Getting started with C# Language
- Learn Tutorial
- How to Start Learning C# While Still in College
- Awesome Book
- Awesome Community
- Awesome Course
- Awesome Tutorial
- Awesome YouTube
- .NET Compiler Platform (Roslyn)
- Access Modifiers
- Access network shared folder with username and password
- Accessing Databases
- Action Filters
- Aliases of built-in types
- An overview of c# collections
- Anonymous types
- Arrays
- ASP.NET Identity
- AssemblyInfo.cs Examples
- Async/await, Backgroundworker, Task and Thread Examples
- Async-Await
- Asynchronous Socket
- Attributes
- BackgroundWorker
- BigInteger
- Binary Serialization
-
BindingList
- Built-in Types
- C# 3.0 Features
- C# 4.0 Features
- C# 5.0 Features
- C# 6.0 Features
- C# 7.0 Features
- C# Authentication handler
- C# Script
- Caching
- Casting
- Checked and Unchecked
- CLSCompliantAttribute
- Code Contracts
- Code Contracts and Assertions
- Collection Initializers
- Comments and regions
- Common String Operations
- Conditional Statements
- Constructors and Finalizers
- Creating a Console Application using a Plain-Text Editor and the C# Compiler (csc.exe)
- Creating Own MessageBox in Windows Form Application
- Creational Design Patterns
- Cryptography (System.Security.Cryptography)
- Data Annotation
- DateTime Methods
- Delegates
- Dependency Injection
- Diagnostics
- Dynamic type
- Enum
- Equality Operator
- Equals and GetHashCode
- Events
- Exception Handling
- Expression Trees
- Extension Methods
- File and Stream I/O
- FileSystemWatcher
- Func delegates
- Function with multiple return values
- Functional Programming
- Garbage Collector in .Net
- Generating Random Numbers in C#
- Generic Lambda Query Builder
- Generics
- Getting Started: Json with C#
- Guid
- Handling FormatException when converting string to other types
- Hash Functions
- How to use C# Structs to create a Union type (Similar to C Unions)
- ICloneable
- IComparable
- IDisposable interface
- IEnumerable
- ILGenerator
- Immutability
- Implementing Decorator Design Pattern
- Implementing Flyweight Design Pattern
- Import Google Contacts
- Including Font Resources
- Indexer
- Inheritance
- Initializing Properties
- INotifyPropertyChanged interface
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- Interoperability
- IQueryable interface
- Iterators
- Keywords
- Lambda expressions
- Lambda Expressions
- LINQ Queries
- Linq to Objects
- LINQ to XML
- Literals
- Lock Statement
- Looping
- Making a variable thread safe
- Methods
- Microsoft.Exchange.WebServices
- Named and Optional Arguments
- Named Arguments
- nameof Operator
- Naming Conventions
- Networking
- Nullable types
- Check if a generic type parameter is a nullable type
- Check if a Nullable has a value
- Default value of nullable types is null
-
Effective usage of underlying Nullable
argument - Get the value of a nullable type
- Getting a default value from a nullable
- Initialising a nullable
- Null-Coalescing Operator
- Null-conditional Operators
- NullReferenceException
- O(n) Algorithm for circular rotation of an array
- Object initializers
- Object Oriented Programming In C#
-
ObservableCollection
- Operators
- Overflow
- Overload Resolution
- Parallel LINQ (PLINQ)
- Partial class and methods
- Performing HTTP requests
- Pointers
- Pointers & Unsafe Code
- Polymorphism
- Preprocessor directives
- Properties
- Reactive Extensions (Rx)
- Read & Understand Stacktraces
- Reading and writing .zip files
- Recursion
- Reflection
- Regex Parsing
- Runtime Compile
- Singleton Implementation
- Static Classes
- Stopwatches
- Stream
- String Concatenate
- String Escape Sequences
- String Interpolation
- String Manipulation
- String.Format
- StringBuilder
- Structs
- Structural Design Patterns
- Synchronization Context in Async-Await
- System.DirectoryServices.Protocols.LdapConnection
- System.Management.Automation
- T4 Code Generation
- Task Parallel Library
- Task Parallel Library (TPL) Dataflow Constructs
- Threading
- Timers
- Tuples
- Type Conversion
- Unsafe Code in .NET
- Using Directive
- Using json.net
- Using SQLite in C#
- Using Statement
- Value type vs Reference type
- Verbatim Strings
- Windows Communication Foundation
- XDocument and the System.Xml.Linq namespace
- XML Documentation Comments
- XmlDocument and the System.Xml namespace
- Yield Keyword
C# Language Nullable types
Syntax
Nullable<int> i = 10;- int? j = 11;
- int? k = null;
- DateTime? DateOfBirth = DateTime.Now;
- decimal? Amount = 1.0m;
- bool? IsAvailable = true;
- char? Letter = 'a';
- (type)? variableName
Remarks
Nullable types can represent all the values of an underlying type as well as null.
The syntax T? is shorthand for Nullable<T>
Nullable values are System.ValueType objects actually, so they can be boxed and unboxed. Also, null value of a nullable object is not the same as null value of a reference object, it's just a flag.
When a nullable object boxing, the null value is converted to null reference, and non-null value is converted to non-nullable underlying type.
DateTime? dt = null;
var o = (object)dt;
var result = (o == null); // is true
DateTime? dt = new DateTime(2015, 12, 11);
var o = (object)dt;
var dt2 = (DateTime)dt; // correct cause o contains DateTime value
The second rule leads to correct, but paradoxical code:
DateTime? dt = new DateTime(2015, 12, 11);
var o = (object)dt;
var type = o.GetType(); // is DateTime, not Nullable<DateTime>
In short form:
DateTime? dt = new DateTime(2015, 12, 11);
var type = dt.GetType(); // is DateTime, not Nullable<DateTime>
Nullable types Related Examples
- Check if a generic type parameter is a nullable type
- Check if a Nullable has a value
- Default value of nullable types is null
-
Effective usage of underlying Nullable
argument - Get the value of a nullable type
- Getting a default value from a nullable
- Initialising a nullable
