using System;
using System.Collections.Generic;

List<int> numbers = new() { 1, 2, 3, 4, 5 };

foreach (var n in numbers)
    Console.WriteLine(n);

numbers.ForEach(Console.WriteLine);

numbers.ForEach(n => Console.WriteLine(n * n));

Ссылочка на плейлист: YouTube 🖤

using System;
using System.IO;
using System.Threading.Tasks;

FileStream fs = new FileStream("data.txt", FileMode.Open);
StreamReader reader = new StreamReader(fs);
string text = await reader.ReadToEndAsync();

await using FileStream fs = new FileStream("data.txt", FileMode.Open, FileAccess.Read, FileShare.Read, 4096, true);
using StreamReader reader = new StreamReader(fs);

string text = await reader.ReadToEndAsync();
Console.WriteLine(text);

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