List patterns in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if the list starts with 1, 2, 3 using list pattern.

C Sharp (C#)

int[] numbers = {1, 2, 3, 4, 5};
if (numbers is [1]) {
    Console.WriteLine("Starts with 1, 2, 3");
}

Drag options to blanks, or click blank then click option'

A[1, 2, 3, ..]

B[1, 2, 3]

C[.., 1, 2, 3]

D[1, .., 3]

Attempts:

3 left

💡 Hint

Common Mistakes

Using exact length pattern without .. causes mismatch if list is longer.

Placing .. in the wrong position.

The pattern [1, 2, 3, ..] matches arrays starting with 1, 2, 3 followed by any elements.

2fill in blank

medium

Complete the code to check if the list has exactly two elements 5 and 10.

C Sharp (C#)

int[] values = {5, 10};
if (values is [1]) {
    Console.WriteLine("Exactly 5 and 10");
}

Drag options to blanks, or click blank then click option'

A[5, 10]

B[5, ..]

C[.., 10]

D[5]

Attempts:

3 left

💡 Hint

Common Mistakes

Using .. which allows extra elements.

Using a single element pattern.

The pattern [5, 10] matches arrays with exactly two elements 5 and 10.

3fill in blank

hard

Fix the error in the pattern to check if the list starts with 0 and ends with 9.

C Sharp (C#)

int[] arr = {0, 1, 2, 3, 9};
if (arr is [1]) {
    Console.WriteLine("Starts with 0 and ends with 9");
}

Drag options to blanks, or click blank then click option'

A[0, 9]

B[0, .., 9]

C[.., 0, 9]

D[0, ..]

Attempts:

3 left

💡 Hint

Common Mistakes

Using pattern without .. which matches only two elements.

Placing .. incorrectly.

The pattern [0, .., 9] matches arrays starting with 0 and ending with 9 with any elements in between.

4fill in blank

hard

Fill both blanks to match a list starting with 7 and having any elements after.

C Sharp (C#)

int[] data = {7, 8, 9};
if (data is [1]) {
    Console.WriteLine("Starts with 7");
}

if (data is [2]) {
    Console.WriteLine("Starts with 7 and 8");
}

Drag options to blanks, or click blank then click option'

A[7, ..]

B[7]

C[7, 8, ..]

D[.., 7]

Attempts:

3 left

💡 Hint

Common Mistakes

Using patterns without .. which require exact length.

Confusing the order of elements.

The first pattern [7, ..] matches any list starting with 7.
The second pattern [7, 8, ..] matches lists starting with 7 and 8.

5fill in blank

hard

Fill all three blanks to create a dictionary from a list where keys are uppercase strings and values are their lengths if length > 3.

C Sharp (C#)

var words = new List<string> {"apple", "bat", "carrot", "dog"};
var result = words.ToDictionary(
    [1] => [2].ToUpper(),
    [3] => [3].Length
).Where(kv => kv.Value > 3).ToDictionary(kv => kv.Key, kv => kv.Value);

Drag options to blanks, or click blank then click option'

Aword

Ditem

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names causing errors.

Not converting to uppercase for keys.

All blanks use the same variable word to represent each string in the list.
The key selector converts word to uppercase.
The value selector gets the length of word.