QUESTION 1 / 15 · TYPES & VALUESEasy
What does this print?
struct P { public int X; }var a = new P { X = 1 };var b = a;b.X = 2;Console.Write(a.X);What this C# test measures, in short
This test checks whether you can predict what real C# does: when a value is copied versus shared, how strings and equality behave, which method a call reaches, when LINQ actually runs, and how async, nullable types and the ?? operator work.
Snippets assume C# 12 on .NET 8 with top-level statements. The questions are our own and not standardised against a population, so treat the result as a knowledge check, not a certification.
By What's Your IQ · Reviewed 4 Oct 2026- Format
- 15 predict-the-output questions, 4 options each
- Topics
- Types and values, strings and equality, classes, LINQ, async and nullability
- Version
- C# 12, .NET 8
- Language
- Designed at Microsoft by Anders Hejlsberg; released 2002
QUESTIONS 1 AND 2, SIDE BY SIDE
Copy the value, or copy the arrow?
STACK
aP { X = 1 }
HEAP
(nothing)
C# 2 → C# 12
The same code, twenty years apart
OLD STYLE
public class Pt { public int X { get; private set; } public int Y { get; private set; } public Pt(int x, int y) { X = x; Y = y; } public override bool Equals(object o) { … } public override int GetHashCode() { … }}MODERN
public record Pt(int X, int Y);
Records (C# 9) generate the constructor, properties, value equality, hashing, ToString and with-expressions in one line.
One designer, two languagesAnders Hejlsberg also created TypeScriptBefore Microsoft he wrote Turbo Pascal and led Delphi. Ideas like async/await travelled from C# into TypeScript and beyond.1
2002C# 1.0 with .NET. Garbage-collected like Java, but with structs, properties and events built in.1
2007 · C# 3LINQ. Lambdas and query syntax made collections queryable like a database.2
2012 · C# 5async/await. Asynchronous code that reads like ordinary code. JavaScript, Python, Rust and others later adopted the same keywords.2
2016 → 2019Open and cross-platform. .NET Core ran on Linux and macOS and was open-sourced; C# 8 added nullable reference types.2
- Hejlsberg, A., Torgersen, M., Wiltamuth, S., & Golde, P. (2010). The C# programming language (4th ed.). Addison-Wesley.
- Microsoft. The history of C#. Microsoft Learn.