The Guid
struct is a value type in C# and has a default value of all zeroes, which represents an empty Guid
. To represent the absence of a value, you can assign a null value to a Guid
variable using the nullable type syntax.
Here is an example of declaring a nullable Guid
variable:
Guid? nullableGuid = null;
In this case, the nullableGuid
the variable is declared as a nullable Guid
by appending a ?
to the Guid
type. This allows the variable to accept a null value, in addition to any valid Guid
value.
You can also check if a Guid
the variable is null using the Nullable<T>.HasValue
property or the null-coalescing operator (??
).
Example Program to Implement Nullable Guid in C#
using System; namespace ConsoleApp1 { class Program { static void Main(string[] args) { // Declare a nullable Guid variable Guid? nullableGuid = null; // Prompt the user to enter a Guid Console.Write("Enter a Guid (or press enter to skip): "); string input = Console.ReadLine(); // Try to parse the input as a Guid if (!string.IsNullOrEmpty(input)) { Guid guid; if (Guid.TryParse(input, out guid)) { nullableGuid = guid; } else { Console.WriteLine("Invalid Guid format."); Console.ReadKey(); return; } } // Display the entered Guid, if any if (nullableGuid.HasValue) { Console.WriteLine("Entered Guid: " + nullableGuid.Value); } else { Console.WriteLine("No Guid was entered."); } // Wait for the user to press a key before closing the console Console.ReadKey(); } } }
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