Understanding Arrays
with Practical Examples

What is an Array?

An array is a data structure that stores a fixed-size, ordered collection of elements of the same type. Each element in an array is identified by an index or position.

Imagine an array as a row of boxes where each box holds a value, and each box is labeled with an index starting from 0.

Why Do We Use Arrays?

• To group similar data elements together.
• To access elements quickly using indexes.
• To perform batch operations like sorting, filtering, and iterating.

Declaring and Initializing an Array

Here’s how you can declare and initialize an array in pseudocode:

Declare array of size 5
array = [10, 20, 30, 40, 50]

This array holds 5 integers. Index starts from 0 and goes to 4.

Accessing Array Elements

You can access or modify elements using their index:

value = array[2]    // Accesses the 3rd element which is 30
array[4] = 100      // Changes the 5th element to 100

Output:

value = 30
array = [10, 20, 30, 40, 100]

Question:

What happens if you try to access array[5] in the above example?

Answer: You’ll get an error or unexpected behavior because index 5 is out of bounds. The valid indices are 0 to 4 for an array of size 5.

Iterating Through an Array

To perform operations on each element, you can loop through the array:

for i from 0 to length of array - 1 do
  print(array[i])
end for

Output:

10
20
30
40
100

Common Operations on Arrays

1. Finding the Maximum Element

max = array[0]
for i from 1 to length of array - 1 do
  if array[i] > max then
    max = array[i]
  end if
end for
print(max)

Output:

100

2. Calculating the Sum of All Elements

sum = 0
for i from 0 to length of array - 1 do
  sum = sum + array[i]
end for
print(sum)

Output:

200

Question:

Can an array hold elements of different types?

Answer: In most programming languages, arrays are homogeneous, meaning all elements should be of the same type (like all integers or all strings).

Limitations of Arrays

• Fixed size: You must define the size upfront.
• Inefficient insertions and deletions (especially in the middle).

Tip:

If you need a dynamic data structure that grows or shrinks, consider using a List or Dynamic Array instead.

Summary

• Arrays store data in a fixed-size, indexed format.
• Elements are accessed using indices, starting from 0.
• They are ideal for fast lookup but less efficient for insertions/deletions.