Array in C++ - Quiz

An array in C++ is used to store multiple values of the same data type in a continuous block of memory.

This allows easy access to elements using an index.

Example:

int a[3] = {10, 20, 30};

All elements are integers and are stored next to each other in memory.

Why other options are incorrect

• A) Different data types ❌ → Arrays store only same data type

• C) Function ❌ → Arrays are not functions

• D) Pointer variable ❌ → An array is not a pointer (though related)

Correct Answer:

B) A collection of same data type elements stored in contiguous memory

Description:
Arrays store multiple values of the same type in consecutive memory locations for efficient access.

To declare an array in C++, you must specify:

• The data type

• The array name

• The number of elements inside square brackets [ ]

int arr[10];

This correctly declares an array that can store 10 integers.

Why other options are incorrect

• A) int arr; ❌ → Declares a single integer, not an array

• B) int arr(10); ❌ → Not valid array syntax

• D) array int arr[10]; ❌ → Invalid C++ syntax

Correct Answer: C) int arr[10];

Description:
int arr[10] is the correct way to declare an array of 10 integers in C++.

In C++, array indexing always starts from 0.

That means:

• The first element of an array is accessed using index 0

• The second element uses index 1, and so on

Example:

int a[3] = {10, 20, 30};

Index-wise access:

• a[0] = 10

• a[1] = 20

• a[2] = 30

Correct Answer: B) 0

Description:
C++ uses zero-based indexing for arrays.

In C++, array indexing starts from 0.

For the array:

int a[5];

• Total elements = 5

• Index values = 0, 1, 2, 3, 4

So, the last index is 4, not 5.

Correct Answer: B) 4

Description:
The highest index of an array is always size − 1.

The declaration:

int x[20];

creates an array that can store 20 elements.

• The number inside the brackets [20] specifies the total number of elements

• Array indexing starts from 0

• Valid indices range from 0 to 19

So even though the last index is 19, the array still contains 20 elements.

Correct Answer: C) 20

Description:
x[20] means the array size is 20, not 19.

The for loop is most commonly used to access array elements because:

• The number of elements in an array is usually known

• It allows easy control of the index using initialization, condition, and increment

Example:

for (int i = 0; i < 5; i++) {
    cout << arr[i];
}

Other loops (while, do-while) can also be used, but they are less convenient for array traversal.
A switch loop cannot be used to iterate over arrays.

Correct Answer: C) for loop

In C++, accessing an array index outside its declared size does not automatically give a compiler error or a guaranteed runtime error.

Instead, it results in undefined behavior.

This means:

• The program may print a garbage value

• It may crash

• Or it may seem to work incorrectly

• The behavior can vary from system to system

C++ does not perform bounds checking on arrays.

Correct Answer: D) Undefined behavior

Description:
Accessing an array index beyond its size leads to unpredictable results, which is called undefined behavior in C++.

In C++, an array must be declared with a size and initialized using curly braces { }.

int a[3] = {1, 2, 3};

This statement:

• Declares an array of 3 integers

• Correctly initializes all elements

Why other options are wrong

• A) int a = {1,2,3}; ❌ → a is not an array

• B) int a[3] = 1,2,3; ❌ → Missing { }

• D) int a(3) = {1,2,3}; ❌ → Invalid array syntax

Correct Answer: C) int a[3] = {1,2,3};

In C++, array indexing starts from 0.

int a[3] = {10, 20, 30};

Index-wise values:

• a[0] = 10

• a[1] = 20

• a[2] = 30

The statement:

cout << a[1];

prints the value at index 1, which is 20.

 Correct Answer: B) 20

Answer: C

A two-dimensional array in C++ stores data in the form of rows and columns, just like a table.

Because of this row–column structure, a two-dimensional array is commonly referred to as a matrix.

Why other options are incorrect

• A) Single array ❌
  A single array refers to a one-dimensional array, not a 2D array.

• B) Pointer array ❌
  A pointer array is an array of pointers, which is different from a 2D array.

• D) String ❌
  A string is a character array, not necessarily two-dimensional.