Record structs in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of record struct with property init

What is the output of this C# code snippet using a record struct?

C Sharp (C#)

public record struct Point(int X, int Y);

var p1 = new Point(3, 4);
var p2 = p1 with { Y = 10 };
Console.WriteLine(p2);

A Point { X = 3, Y = 4 }

B Point { X = 3, Y = 10 }

C Compilation error: 'with' expressions not supported on record structs

D Point { X = 10, Y = 4 }

💡 Hint

Remember that record structs support 'with' expressions to create copies with modifications.

The 'with' expression creates a copy of the record struct with the specified property changed. Here, Y is changed to 10 while X remains 3.

🧠 Conceptual

intermediate

Immutability of record structs

Which statement about record structs in C# is true?

A Record structs are always immutable and cannot have mutable properties.

B Record structs behave exactly like classes in terms of reference equality.

C Record structs can have mutable properties but still provide value equality semantics.

D Record structs cannot have parameterized constructors.

💡 Hint

Think about how record structs differ from classes and normal structs.

Record structs provide value equality and can have mutable properties. They are value types, so they differ from classes in reference behavior.

🔧 Debug

advanced

Fix the error in record struct declaration

This code produces a compilation error. What is the cause?

C Sharp (C#)

public record struct Rectangle
{
    public int Width { get; init; }
    public int Height { get; init; }

    public Rectangle(int width, int height) : this()
    {
        Width = width;
        Height = height;
    }
}

A The constructor must use 'this()' to call the parameterless constructor before assigning properties.

B Record structs cannot have properties with 'init' accessors.

C The properties must be declared as 'readonly' to be used in a record struct.

D The constructor must be removed because record structs cannot have explicit constructors.

💡 Hint

In structs, constructors must initialize all fields and call the parameterless constructor if present.

In C#, struct constructors must call the parameterless constructor (or chain to another constructor) before assigning to properties. Omitting 'this()' causes a compilation error.

📝 Syntax

advanced

Identify the invalid record struct syntax

Which of the following record struct declarations is invalid in C#?

A public record struct Data(int X, int Y) : BaseStruct;

B public record struct Car { public string Model { get; init; } public int Year { get; init; } }

C public record struct Person(string Name, int Age);

D public record struct Point { public int X; public int Y; }

💡 Hint

Consider inheritance rules for structs in C#.

Structs, including record structs, cannot inherit from other structs or classes, so ': BaseStruct' is invalid syntax.

🚀 Application

expert

Value equality behavior of record structs

Given this code, what is the output?

C Sharp (C#)

public record struct Coordinate(int X, int Y);

var c1 = new Coordinate(5, 7);
var c2 = new Coordinate(5, 7);

Console.WriteLine(c1 == c2);
Console.WriteLine(ReferenceEquals(c1, c2));

A False\nTrue

B False\nFalse

C True\nTrue

D True\nFalse

💡 Hint

Record structs provide value equality but are value types, so reference equality behaves differently.

The '==' operator for record structs compares values and returns true. ReferenceEquals returns false because structs are value types and boxed separately.