Generate a UUID in C#

How to Generate a UUID in C#

The C# language, via the .NET Framework, has built-in support for generating Version 4 UUIDs. Here's an example of how you can create a UUID in C# code.

using System;
using System.Diagnostics;

namespace SampleApplication {
    class Program {
        static void Main(string[] args) {
            Guid myuuid = Guid.NewGuid();
            string myuuidAsString = myuuid.ToString();

            Debug.WriteLine("Your UUID is: " + myuuidAsString);
        }
    }
}

Explanation

• On line #7, we use the System.Guid.NewGuid() static method to create a new Guid instance, stored in the variable, myuuid. In .NET, a GUID (Globally Unique Identifier) is equivalent to a UUID.
• On line #8, we use the ToString() method to convert the Guid instance to a string. The string representation of a Guid looks like a standard UUID (i.e. 2e63341a-e627-48ac-bb1a-9d56e2e9cc4f). If you're going to store the UUID in a file, database or model property, or send it via an API call to a different application, you'll almost always need the string representation of the myuuid instance, rather than the myuuid instance itself.
• The output from line #10 will be something like:

  Your UUID is: 2e63341a-e627-48ac-bb1a-9d56e2e9cc4f
  

Convert from a string to a UUID

Although it's rare, in some circumstances you might need to convert from a string representation of a UUID (like the one from line #8 above) back into an instance of Guid.

C# provides for this scenario with a Guid constructor, Guid(string). You can call this method like this:

using System;
using System.Diagnostics;

namespace SampleApplication {
    class Program {
        static void Main(string[] args) {
            Guid myuuid = Guid.NewGuid();
            string myuuidAsString = myuuid.ToString();

            Guid sameUuid = new Guid(myuuidAsString);
            Debug.Assert(sameUuid.Equals(myuuid));
        }
    }
}

Explanation

• Line #10 shows converting the string representation of a UUID into a Guid instance (sameUuid) using the Guid(String) constructor method.
• Line #11 is included to show that the 2 Guid instances are equal.

How can we improve this page? Let us know!