Classes and Objects in C#
15 questions · 12 min · Medium
Collection Classes in C#
Test your knowledge of collection classes in C#, including ArrayList, Hashtable, List, Dictionary, Queue, Stack, and other collection concepts.
- 15
- Questions
- 12 min
- Time limit
- Medium
- Difficulty
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All 15 questions and answers Spoilers: this shows the questions and answers. Try the quiz first! Open
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1. Which namespace contains many of the non-generic collection classes in C#?
- A. System.Collections
- B. System.Collections.Generic
- C. System.CollectionClasses
- D. System.Data.Collections
Show answer
A. System.Collections
The System.Collections namespace contains non-generic collection classes such as ArrayList, Hashtable, Queue, and Stack.
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2. Which generic collection is commonly used to store a strongly typed list of elements?
- A. Hashtable
- B. ArrayList
- C. List<T>
- D. Queue
Show answer
C. List<T>
List<T> is a generic collection that stores elements of a specified type and provides strongly typed access.
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3. Which collection stores elements as key-value pairs?
- A. List<T>
- B. Dictionary<TKey, TValue>
- C. Stack<T>
- D. Queue<T>
Show answer
B. Dictionary<TKey, TValue>
Dictionary<TKey, TValue> stores values using unique keys that are associated with each value.
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4. Which collection follows the First-In-First-Out (FIFO) principle?
- A. Stack<T>
- B. Queue<T>
- C. Dictionary<TKey, TValue>
- D. HashSet<T>
Show answer
B. Queue<T>
A Queue<T> follows FIFO, meaning the first element added is normally the first element removed.
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5. Which collection follows the Last-In-First-Out (LIFO) principle?
- A. Queue<T>
- B. List<T>
- C. Stack<T>
- D. Dictionary<TKey, TValue>
Show answer
C. Stack<T>
A Stack<T> follows LIFO, meaning the most recently added element is normally the first one removed.
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6. Which non-generic collection can store elements of different types and is found in System.Collections?
- A. List<T>
- B. ArrayList
- C. Dictionary<TKey, TValue>
- D. HashSet<T>
Show answer
B. ArrayList
ArrayList is a non-generic collection that can store objects of different types. Generic collections are generally preferred for type safety.
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7. Which collection is designed to store unique elements?
- A. HashSet<T>
- B. List<T>
- C. Queue<T>
- D. Stack<T>
Show answer
A. HashSet<T>
HashSet<T> is designed to store unique elements and does not allow duplicate elements according to its equality comparer.
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8. Which method adds an element to a List<T>?
- A. InsertItem()
- B. Add()
- C. Push()
- D. Enqueue()
Show answer
B. Add()
The Add() method appends an element to a List<T>.
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9. Which method adds an element to a Queue<T>?
- A. Push()
- B. Add()
- C. Enqueue()
- D. Insert()
Show answer
C. Enqueue()
Enqueue() adds an element to the end of a Queue<T>.
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10. Which method adds an element to a Stack<T>?
- A. Push()
- B. Enqueue()
- C. Add()
- D. Append()
Show answer
A. Push()
Push() adds an element to the top of a Stack<T>.
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11. Which method removes and returns the element at the front of a Queue<T>?
- A. Pop()
- B. Remove()
- C. Dequeue()
- D. Delete()
Show answer
C. Dequeue()
Dequeue() removes and returns the element at the beginning of a Queue<T>.
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12. Which method removes and returns the top element of a Stack<T>?
- A. Dequeue()
- B. Pop()
- C. Remove()
- D. Take()
Show answer
B. Pop()
Pop() removes and returns the element at the top of a Stack<T>.
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13. What is a major advantage of generic collections such as List<T> over older non-generic collections such as ArrayList?
- A. They cannot contain objects
- B. They provide compile-time type safety
- C. They can only store strings
- D. They do not support iteration
Show answer
B. They provide compile-time type safety
Generic collections specify the element type, reducing invalid type assignments and avoiding many unnecessary casts.
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14. Which collection is commonly used to map unique keys to values?
- A. Dictionary<TKey, TValue>
- B. Stack<T>
- C. Queue<T>
- D. List<T>
Show answer
A. Dictionary<TKey, TValue>
Dictionary<TKey, TValue> provides a key-value mapping where each key must be unique within the dictionary.
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15. Which interface is commonly implemented by collections that can be enumerated using foreach?
- A. IEnumerable
- B. IDisposable
- C. IComparable
- D. IFormattable
Show answer
A. IEnumerable
IEnumerable provides the basic mechanism for obtaining an enumerator, allowing a collection to be traversed with foreach.