C# is the .NET language for services, desktop apps and games. Its interviews go deep on value versus reference semantics.
Structs versus classes, boxing, async and await state machines, LINQ deferred execution, IDisposable, and nullable reference types.
Where it shows up: Enterprise back ends on .NET, Unity game development, and Windows tooling.
Twenty real C# questions from the library, code snippet included. Nothing here is paraphrased for search engines. It is the same text a signed-in user sees.
IQueryable<Order> q = db.Orders;
var result = q.Where(o => o.Total > 100)
.AsEnumerable()
.Where(o => o.Notes.Contains("urgent"))
.ToList();var items = new List<string> { "a", "b" };
foreach (var item in items)
{
item = item.ToUpper();
}var n = 3.0;var value = null;var nums = new[] { 1, 2, 3, 4 };
var result = nums.Where(n => n % 2 == 0).Select(n => n * 10);
Console.WriteLine(string.Join(",", result));int? x = 5;
Console.WriteLine(x.GetType());struct Point { public int X; }
var a = new Point { X = 5 };
var b = a;
b.X = 99;
Console.WriteLine(a.X);
Console.WriteLine(b.X);double rate = 0.5;
Console.WriteLine($"{rate:P0}");void Print(in int x) => Console.WriteLine(x);int[] arr = { 1, 2, 3 };
int[] copy = arr;
copy[0] = 42;
Console.WriteLine(arr[0]);async Task<int> LoadAsync()
{
var data = await FetchAsync();
return data.Length;
}var query = source.Where(x => x > 0).Select(x => Transform(x));
// query is never iteratedforeach (var item in collection) { /* ... */ }async void Fire()
{
await Task.Delay(10);
throw new InvalidOperationException();
}int Run()
{
try
{
throw new InvalidOperationException();
}
catch (InvalidOperationException)
{
return 1;
}
finally
{
Console.WriteLine("cleanup");
}
}var scores = new Dictionary<string, int>();
// ...try { DoWork(); }
catch (Exception ex)
{
Log(ex);
throw; // vs. throw ex;
}using (var a = new Res("A"))
using (var b = new Res("B"))
{
// work
}static void Print(IEnumerable<object> items) { }
List<string> names = new() { "a", "b" };
Print(names);var d = new Dictionary<string, int>(StringComparer.OrdinalIgnoreCase);
d["Hello"] = 1;
d["HELLO"] = 2;
Console.WriteLine(d.Count + " " + d.Keys.First());We keep the correct answer, the explanation and the scoring behind sign-in so the platform stays honest, which is why the answer options and the worked explanation for every C# question stay behind a free account. Signing in is free and takes a few seconds.
49 distinct C# topics are tagged across the library. These are the real topic labels stored on the questions, not a hand-written list.
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