Blog of Denis VOITURON

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A shorter, more user-friendly GUID

Posted on 2022-04-07

When generating HTML code, you often need a unique identifier. A GUID works fine but it is very long (3297F0F2-35D3-4231-919D-1CFCF4035975). You can shorten it but isn’t there a more optimized (faster) way to generate an identifier in C#?

Here is a class containing several methods.

public class Identifier
    private static Random _rnd = new Random();

    // 8da18880a18a4cd
    public string NewId_FromTicks() => DateTime.Now.Ticks.ToString("x");

    // c9a646d3-9c61-4cb7-bfcd-ee2522c8f633
    public string NewId_FromGuid() => Guid.NewGuid().ToString();

    // 1WIXVZtbA0qKPcZ
    public string NewId_FromGuidBase64() => Convert.ToBase64String(Guid.NewGuid().ToByteArray())
                                                    .Replace("/", "_")
                                                    .Replace("+", "-")
                                                    .Substring(0, 15);
    // 1WIXVZtbA0qKPcZ
    public string NewId_FromGuidShorted() => Guid.NewGuid().ToString("N").Substring(0, 15);

    // 2c6fec62
    public string NewId_FromRandomInt() => _rnd.Next(int.MaxValue).ToString("x");

    // 127d9edf
    public string NewId_FromRandomLong() => _rnd.Next().ToString("x");
    // 127d9edf14385adb
    public string NewId_FromRandomDoubleLong() => $"{_rnd.Next().ToString("x")}{_rnd.Next().ToString("x")}";

The following table shows the average execution time of these methods, using the benchmark library BenchmarkDotNet.

BenchmarkDotNet=v0.13.1, OS=Windows 8 (6.2.9200.556)
Intel Core i7-1065G7 CPU 1.30GHz, 1 CPU, 8 logical and 4 physical cores
.NET SDK=6.0.201
  [Host]     : .NET 6.0.3 (6.0.322.12309), X64 RyuJIT
  DefaultJob : .NET 6.0.3 (6.0.322.12309), X64 RyuJIT

| Method           | Example                              |  Mean     |
| From Rnd Long:     10aad4a0                                51.14 ns |
| From Rnd Int:      4a9d0f06                                51.59 ns |
| From Rnd Long:     6aa977f03314e4b4                       115.12 ns |
| From Ticks:        8da188a929219fab                       174.41 ns |
| From Guid Base64:  aRk3NU0b0ka04Oqc                       206.67 ns |
| From Guid:         25ee3842-0c33-4a63-9b83-a7d1c0266809   224.59 ns |
| From Guid Shorted: 6ee0e232196b4a9                        237.51 ns |

A good compromise is the use of the method NewId_FromRandomDoubleLong. which returns a value over 12 characters and much faster than the GUID. This value is acceptable when generating identifiers from a web server or a standalone application. It is still preferable to use a GUID when working with several servers or data exchanges between clients.



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