C# Nullable

C# csharp-nullable for beginners and professionals with examples on overloading, method overriding, inheritance, aggregation, base, polymorphism, sealed, abstract, interface, namespaces, exception handling, file io, collections, multithreading, reflection etc.

<< Back to C-SHARP

next → ← prev

C# Nullable

In C#, Nullable is a concept that allows a type to hold an additional value null. In other words, we can make a variable Nullable, so, it can hold additional null value. All Nullable variables are the instances of System.Nullable<T> struct.

The concept of Nullable is useful when we deal with databases that contain elements that may not be assigned a value.

C# provides two different ways to create Nullable types.

By creating System.Nullable instance,
By using ? operator

Note: we cannot create Nullable of reference type variable.

C# System.Nullable Example

In the following example, we are making Nullable with the help of System.Nullable namespace.

// NullableExample2.cs

using System;
namespace CSharpFeatures
{
    class NullableExample2
    {
        static void Main(string[] args)
        {
            Nullable<int> a = 10;
            Nullable<double> d = 10.10;
            Nullable<char> c = 'S';
            Nullable<bool> b = false;
            // Displaying value
            Console.WriteLine(a.Value);
            // assigning null values
            a = null;
            d = null;
            c = null;
            b = null;
            // Checking, does "a" contain value ?
            if (a.HasValue)
            {
                Console.WriteLine(a.Value);
            }
            if(a == null)
             Console.WriteLine("It contains null value");
        }
    }
}

Output:

Compile the program by using the following command.

csc NullableExample2.cs

Run the program by using following command.

NullableExample2.exe

C# Nullable using ? Operator Example 1

There is no significant difference between using of either System.Nullable or ? operator. We can use anyone as per our comfort.

// NullableExample.cs

using System;
namespace CSharpFeatures
{
    class NullableExample
    {
        static void Main(string[] args)
        {
            // Integer nullable
            int? a = 10;
            // Float nullable
            double? f = 10.10;
            // Boolean nullable
            bool? b = false;
            // Char nullable
            char? c = 'S';
            // Checking value is present or not
            if (a.HasValue)
            {
                Console.WriteLine(a.Value);
            }
            else Console.WriteLine("a contains null value");
            // Assigning null value
            a = null;
            if (a.HasValue) // Checking again
            {
                Console.WriteLine(a.Value);
            }
            else Console.WriteLine("a contains null value");
        }
    }
}

Output:

10
a contains null value

C# Nullable using ? Operator Example 2

using System;
namespace CSharpFeatures
{
    class NullableExample2
    {
        static void Main(string[] args)
        {
            Nullable<int> a = 10;
            Nullable<double> d = 10.10;
            Nullable<char> c = 'S';
            Nullable<bool> b = false;
            // Displaying value
            Console.WriteLine(a.Value);
            // assigning null values
            a = null;
            d = null;
            c = null;
            b = null;
            // Checking, does "a" contain value ?
            if (a.HasValue)
            {
                Console.WriteLine(a.Value);
            }
            if(a == null)
             Console.WriteLine("It contains null value");
        }
    }
}

Output:

10
It contains null value

Next TopicC# Delegate Covariance

← prev next →

.Net

.NET Array Dictionary List String 2D Async DataTable Dates DateTime Enum File For Foreach Format IEnumerable If IndexOf Lambda LINQ Parse Path Process Property Regex Replace Sort Split Static StringBuilder Substring Switch Tuple

Java

Core Array ArrayList HashMap String 2D Cast Character Console Deque Duplicates File For Format HashSet If IndexOf Lambda Math ParseInt Process Random Regex Replace Sort Split StringBuilder Substring Switch Vector While

TheDeveloperBlog.com

C# Nullable

C# Nullable

Note: we cannot create Nullable of reference type variable.

C# System.Nullable Example

C# Nullable using ? Operator Example 1

Related Links:

.Net

Java

Related Links