Expression-bodied lambdas in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of an expression-bodied lambda with arithmetic

What is the output of this C# code using an expression-bodied lambda?

C Sharp (C#)

Func<int, int> square = x => x * x;
Console.WriteLine(square(5));

A 10

B 25

C 5

D Compilation error

💡 Hint

Remember that the lambda returns the result of x multiplied by itself.

The lambda takes an integer x and returns x * x. For input 5, the output is 25.

❓ Predict Output

intermediate

Output of expression-bodied lambda with string interpolation

What does this expression-bodied lambda print?

C Sharp (C#)

Func<string, string> greet = name => $"Hello, {name}!";
Console.WriteLine(greet("Anna"));

A Hello, Anna!

B Hello, {name}!

C greet(Anna)

D Compilation error

💡 Hint

The lambda uses string interpolation to insert the name.

The lambda returns the string with the name inserted. For "Anna", it prints "Hello, Anna!".

🔧 Debug

advanced

Identify the error in this expression-bodied lambda

What error does this code produce?

C Sharp (C#)

Func<int, int> add = x => { x + 2; };
Console.WriteLine(add(3));

A Compilation error: Missing return statement

B Outputs 5

C Outputs 3

D Runtime error: NullReferenceException

💡 Hint

Expression-bodied lambdas must return a value directly without braces or must use return inside braces.

The lambda uses braces but does not have a return statement, causing a compilation error.

❓ Predict Output

advanced

Output of expression-bodied lambda with conditional operator

What is the output of this code?

C Sharp (C#)

Func<int, string> checkEven = n => n % 2 == 0 ? "Even" : "Odd";
Console.WriteLine(checkEven(7));

A 7

B Even

C Compilation error

D Odd

💡 Hint

The lambda returns "Even" if the number is divisible by 2, otherwise "Odd".

7 is not divisible by 2, so the lambda returns "Odd".

❓ Predict Output

expert

Output of nested expression-bodied lambdas

What is the output of this nested expression-bodied lambda code?

C Sharp (C#)

Func<int, Func<int, int>> multiplier = x => y => x * y;
var times3 = multiplier(3);
Console.WriteLine(times3(4));

A 7

B 3

C 12

D Compilation error

💡 Hint

The outer lambda returns another lambda that multiplies two numbers.

multiplier(3) returns a lambda that multiplies its input by 3. times3(4) returns 3 * 4 = 12.