Python Coding challenge - Day 1212| What is the output of the following Python Code?

 

Code Explanation:

🔹 1. Importing the array Class

from array import array

✅ Explanation

array is imported from Python's built-in array module.

Unlike a Python list, an array stores only one type of data.

Arrays are more memory-efficient than lists when storing many numbers.

Think of an array as a train where every compartment must carry the same type of passenger.

Python List

↓

Can Store

1

"Python"

5.5

Array

↓

Can Store

Only One Data Type

🔹 2. Creating an Integer Array

nums = array('i', [1, 2, 3])

✅ Explanation

Here Python creates an array.

Syntax:

array(typecode, iterable)

There are two parts:

Type Code

'i'

means

Signed Integer

Common type codes:

Type Code Meaning

'i' Integer

'f' Float

'd' Double

'u' Unicode Character

The second argument is

[1, 2, 3]

These values are copied into the array.

Current memory:

nums

↓

array('i',[1,2,3])

🔹 3. Understanding the Array

Current array:

Index

0   1   2

↓

1   2   3

Unlike a list,

array('i')

cannot store:

"Hello"

or

5.5

because every element must be an integer.

🔹 4. Appending a New Value

nums.append(4)

✅ Explanation

append() adds a new element at the end of the array.

Before:

array('i')

↓

1

2

3

After appending:

array('i')

↓

1

2

3

4

Current memory:

nums

↓

array('i',[1,2,3,4])

🔹 5. Calling tolist()

nums.tolist()

✅ Explanation

An array object is not a normal Python list.

The tolist() method converts the array into a standard Python list.

Before conversion:

array

↓

array('i',[1,2,3,4])

After conversion:

List

↓

[1,2,3,4]

No values change—only the data structure changes.

🔹 6. Printing the List

print(nums.tolist())

✅ Explanation

Python prints the converted list.

Output:

[1, 2, 3, 4]

🎯 Final Output

[1, 2, 3, 4]

Book:  700 Days Python Coding Challenges with Explanation