Write a text file.
Write a C# string to a UTF-8 file.
using System;
using System.IO;
using System.Linq;
using System.Collections.Generic;
using System.Text.Json;
File.WriteAllText("notes.txt", "hello\n");
Console.WriteLine("Saved notes.txt");Expected output EXAMPLE
Saved notes.txt
Details
Use Program.cs in a .NET 8 console project (dotnet new console --framework net8.0), then dotnet run. Uses only the .NET standard libraries.
Replaces an existing notes.txt file.
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
62bada08021e7c3c748c711aacb2f0417d81c0a43a5222a6fca3546505dce26e- 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
Saved notes.txt
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.
Additional assertions that passed
Checks recorded by the test harness. Where Python assertions are shown, browser cases use Playwright and simulator cases may inspect pin transitions: result.stdout is captured output, work is the temporary directory, and Path is pathlib.Path. The harness also imports json and csv.
assert Path('notes.txt').read_text() == 'hello\n'