2.1 Arrays

• What is an array in computer science?

  An ordered collection
• In an array, elements are arranged in a specific sequence
• What is a requirement for the data type of elements in an array?

  Must be the same
• Elements in an array can be accessed directly using their numerical index.
• Array elements are the individual values
• Where are array elements stored in memory?

  Contiguously
• All elements in an array must be of the same data type.
• What is the typical starting index of an array?

  0
• What is the syntax for accessing an array element in most programming languages?

  $arrayName[index]$
• Steps for initializing an array

  1️⃣ Declare the array

  2️⃣ Allocate memory for the array

  3️⃣ Assign initial values to elements
• Static initialization assigns values at the time of declaration.
• In dynamic initialization, values are assigned during program execution
• What are common operations performed on arrays?

  Adding, updating, deleting
• Adding an element to a full array may require resizing, which has a time complexity of $O(n)$.
• What are common array operations?

  Adding, updating, deleting, searching
• Inserting an element into an array may require resizing
• Adding an element to an array has a time complexity of $O(1)$ on average.
• The time complexity for adding to an array when resizing is needed is O(n)</latex>
• What does updating an array element involve?

  Modifying its value
• Updating an array element has a time complexity of $O(1)$.
• Deleting an element from an array may involve shifting other elements
• Deleting an element from an array has a time complexity of $O(n)$ due to shifting elements.
• What is the purpose of searching in an array?

  Locating a specific element
• The time complexity for searching in an array using linear search is $O(n)$
• What are array elements defined as?

  Individual values stored in an array
• Array elements are stored randomly in memory.

  False
• Array elements are accessed using their numerical index
• What is a key constraint regarding the data type of array elements?

  All elements must be of the same type
• Array indexing begins at 1.

  False
• Array indexing involves accessing elements using their position
• What is the syntax for array indexing?

  arrayName[index]</latex>
• What are the two main methods of array initialization?

  Static and dynamic
• Static initialization assigns values at the time of declaration
• Dynamic initialization assigns values during program execution.
• What is the syntax for static initialization in C++?

  \int numbers[] = {10, 20, 30};</latex>
• Match the array operation with its description:

  Adding ↔️ Inserts an element into the array

  Updating ↔️ Modifies an existing element

  Deleting ↔️ Removes an element from the array

  Searching ↔️ Locates a specific element
• Adding an element to an array always takes $O(1)$ complexity.


  False
• What is the time complexity of updating an array element?

  $O(1)$
• Deleting an element from an array requires shifting other elements, resulting in a time complexity of $O(n)$
• What is the time complexity of searching for an element in an array?

  $O(n)$