Zip operation in C Sharp (C#) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the Zip method do in C#?

The Zip method combines two sequences element-by-element into a single sequence of pairs or results from a function.

beginner

How does Zip handle sequences of different lengths?

The Zip method stops combining elements when the shortest sequence ends, ignoring extra elements in the longer sequence.

beginner

Show a simple example of Zip combining two integer arrays.

Example:<br>

var a = new[] {1, 2, 3};
var b = new[] {4, 5, 6};
var zipped = a.Zip(b, (x, y) => x + y);
// Result: [5, 7, 9]

intermediate

Can Zip be used with sequences of different types?

Yes, Zip can combine sequences of different types by specifying a result selector function that defines how to combine elements.

beginner

What namespace must be included to use Zip in C#?

You must include using System.Linq; to use the Zip method.

What happens if the two sequences passed to Zip have different lengths?

A An exception is thrown.

B The result length matches the longer sequence.

C The result length matches the shorter sequence.

D The sequences are padded with default values.

The Zip method stops combining elements when the shortest sequence ends.

Which namespace is required to use Zip in C#?

A System.Collections.Generic

B System.Linq

C System.Text

D System.IO

Zip is part of LINQ, so System.Linq is required.

What does this code return?<br>

var a = new[] {1, 2};
var b = new[] {3, 4, 5};
var result = a.Zip(b, (x, y) => x * y).ToList();

A [3, 8]

B [3, 8, 5]

C [1, 2]

D [3, 4]

The result length matches the shorter array (length 2), so only first two pairs are multiplied.

Can Zip combine sequences of different types?

A Yes, by providing a function to combine elements.

B Yes, but only if they are numeric types.

C No, both sequences must be the same type.

D Only if you cast them first.

Zip allows combining different types by specifying a result selector function.

What is the output of this code?<br>

var names = new[] {"Anna", "Bob"};
var ages = new[] {25, 30};
var zipped = names.Zip(ages, (name, age) => $"{name} is {age} years old");
foreach(var s in zipped) Console.WriteLine(s);

A 25 is Anna years old\n30 is Bob years old

B Error

C Anna25\nBob30

D Anna is 25 years old\nBob is 30 years old

The Zip combines names and ages into formatted strings.

Explain how the Zip method works in C# and give a simple example.

Think about pairing elements from two lists.

What happens if the sequences passed to Zip have different lengths? How can you handle this in your code?

Consider what happens to leftover elements.