Convert Unix seconds to an offset-aware timestamp.

C#: DateTimeOffset preserves the UTC offset explicitly.

C# Program.cs
using System;
using System.IO;
using System.Linq;
using System.Text;
using System.Text.Json;
using System.Text.RegularExpressions;
using System.Collections.Generic;
using System.Globalization;
using System.Security.Cryptography;
using System.Threading;
using System.Threading.Tasks;

Console.WriteLine(DateTimeOffset.FromUnixTimeSeconds(0).ToString("yyyy-MM-dd HH:mm:ss zzz", CultureInfo.InvariantCulture));

Expected output EXAMPLE

1970-01-01 00:00:00 +00:00

Details

Use Program.cs in a .NET 8 console project and run dotnet run. Uses only the .NET standard libraries. DateTimeOffset preserves the UTC offset explicitly.

✓ Verified

Tested on Ubuntu 24.04.5 LTS · · 8.0.425 · libc6 2.39-0ubuntu8.9

Test inputs, results and environment

The exact published code ran in a dedicated Linux test container with prepared inputs. Unprivileged snippet process, external networking disabled, read-only root filesystem, and a fresh temporary working directory. Fixtures and output records are isolated from the application database. Testing covers this example and its stated checks, not every input, operating system, or runtime version. The Linux container shares its host's kernel; this is not a native Windows test.

Architecture / host kernel
x86_64 / 6.18.54.1-microsoft-standard-WSL2
Snippet identity / locale
uid=65534, gid=65534 (unprivileged) / C.UTF-8
Interpreter invocation
dotnet build --no-restore && dotnet out/csharp.dll
Container image ID
sha256:32dc2d998158b6554c99b73b533f423696a0f3e31e8cbea9db10b5eee9a2fadd
Code SHA-256
bfa5eaf3f8dd383b975d1ccd99a05de7dbe4b07f65f3ebcd9a3f480b301a437c
Dependencies
libc6 2.39-0ubuntu8.9

Test input setup

These are the prepared inputs used by the test harness. See Details above for the prerequisites and how to run this example.

# No input files required.

Observed standard output

1970-01-01 00:00:00 +00:00

Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.