Zip operation in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Zip operation?

Consider the following C# code using Zip to combine two arrays. What will be printed?

C Sharp (C#)

var numbers = new[] {1, 2, 3};
var words = new[] {"one", "two", "three"};
var zipped = numbers.Zip(words, (n, w) => $"{n}-{w}");
foreach (var item in zipped) {
    Console.WriteLine(item);
}

A one-1\ntwo-2\nthree-3

B 1\n2\n3\none\ntwo\nthree

C Compilation error

D 1-one\n2-two\n3-three

💡 Hint

Zip pairs elements from two sequences in order.

The Zip method pairs elements from the first and second arrays by index, then applies the lambda to create strings like "1-one".

❓ Predict Output

intermediate

What is the output when sequences have different lengths?

What will this C# code print when using Zip on arrays of different lengths?

C Sharp (C#)

var a = new[] {10, 20, 30, 40};
var b = new[] {"a", "b"};
var zipped = a.Zip(b, (x, y) => $"{x}{y}");
foreach (var s in zipped) Console.WriteLine(s);

A Runtime exception

B 10a\n20b

C 10a\n20b\n30b\n40b

D 10a\n20b\n30\n40

💡 Hint

Zip stops at the shortest sequence length.

Zip pairs elements until one sequence runs out. Here, only first two pairs are zipped.

🔧 Debug

advanced

What error does this Zip code cause?

What error will this C# code produce when run?

C Sharp (C#)

var list1 = new List<int> {1, 2, 3};
List<string> list2 = null;
var zipped = list1.Zip(list2, (x, y) => x + y.Length);
foreach (var item in zipped) Console.WriteLine(item);

A NullReferenceException

B ArgumentNullException

C No error, prints 3 lines

D Compilation error

💡 Hint

Check what happens if one sequence is null.

Calling Zip with a null second sequence causes a NullReferenceException at runtime.

❓ Predict Output

advanced

What is the output of this Zip with index?

What will this C# code print?

C Sharp (C#)

var nums = new[] {5, 10, 15};
var words = new[] {"five", "ten", "fifteen"};
var zipped = nums.Zip(words, (n, w) => $"{w}:{n}");
var indexed = zipped.Select((s, i) => $"{i}-{s}");
foreach (var item in indexed) Console.WriteLine(item);

A 0-five:5\n1-ten:10\n2-fifteen:15

B Compilation error

C 5-five\n10-ten\n15-fifteen

D five:5\nten:10\nfifteen:15

💡 Hint

Select with index adds the position before each string.

Zip pairs elements, then Select adds the index before each pair string.

🧠 Conceptual

expert

How many items are in the result of this Zip?

Given these sequences, how many items will the Zip produce?

C Sharp (C#)

var seq1 = Enumerable.Range(1, 100);
var seq2 = Enumerable.Range(1, 50);
var result = seq1.Zip(seq2, (x, y) => x + y);

A 150

B 100

C 50

D 0

💡 Hint

Zip stops at the shortest sequence length.

Zip produces as many items as the shortest input sequence length, which is 50 here.