How it works
Directory.CreateDirectory makes the out folder if it is missing. Path.Combine joins folder and file names. WriteAllLines writes one line per item, and ReadAllLines reads them back. After the run, out/report.txt appears under the output as a written file. It joins the project only if you tap Add to project.
A working example
Directory.CreateDirectory("out");
var path = Path.Combine("out", "report.txt");
File.WriteAllLines(path, new[] { "paid 12.50", "paid 4.25" });
var lines = File.ReadAllLines(path);
Console.WriteLine($"{lines.Length} lines in {path}");
Console.WriteLine(lines[0]);Expected output
2 lines in out/report.txt paid 12.50
Try this
Write to a folder of its own so it is easy to find.
Write to a folder of its own so it is easy to find.