Dictionary key-value collection in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a new dictionary in C#.

C Sharp (C#)

var dict = new Dictionary<string, int>[1];

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

A{}

B<>

C[]

D()

Attempts:

3 left

💡 Hint

Common Mistakes

Using curly braces {} instead of parentheses () to instantiate the dictionary.

Using angle brackets <> which are for generic type parameters, not instantiation.

In C#, to create a new dictionary, you use parentheses after the constructor name. To initialize with elements, you use curly braces.

2fill in blank

medium

Complete the code to add a key-value pair to the dictionary.

C Sharp (C#)

dict.[1]("apple", 5);

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AInsert

BPut

CAdd

DSet

Attempts:

3 left

💡 Hint

Common Mistakes

Using Insert or Put which are not dictionary methods in C#.

Using Set which is not a method for adding items to a dictionary.

The Add method is used to add a new key-value pair to a dictionary in C#.

3fill in blank

hard

Fix the error in accessing a value by key from the dictionary.

C Sharp (C#)

int count = dict[[1]];

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Acount

B"apple"

Capple

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using the key without quotes which causes a compile error.

Using a number or variable name instead of the string key.

Dictionary keys of type string must be accessed using quotes around the key name.

4fill in blank

hard

Fill both blanks to check if a key exists and get its value safely.

C Sharp (C#)

if (dict.[1]("banana", out int [2])) {
    Console.WriteLine([2]);
}

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ATryGetValue

BContainsKey

Cvalue

Dresult

Attempts:

3 left

💡 Hint

Common Mistakes

Using ContainsKey which only checks existence but does not get the value.

Using variable names that are not declared or mismatched.

TryGetValue checks if the key exists and outputs the value to the variable provided.

5fill in blank

hard

Fill all three blanks to create a dictionary from a list of keys with initial value 0.

C Sharp (C#)

var keys = new List<string> {"a", "b", "c"};
var dict = keys.ToDictionary([1] => [2], [3] => 0);

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

Akey

Bk

C_

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names in the two lambdas which causes errors.

Using underscore '_' as a variable name in this context.

The lambda uses the same variable name for key selector and value selector; 'x' is a common choice.