Chapter 4: Input & Output Operations

4.1 Chapter Overview

Input and output operations are important because they allow a Python program to communicate with users. Output means displaying information to the user, while input means accepting information from the user.

In real applications, users enter names, marks, prices, quantities, passwords, email addresses, and many other values. Python accepts these values using the input() function and displays results using the print() function.

4.2 Chapter Objectives

• Understand the purpose of input and output operations.
• Use print() to display output in Python.
• Use input() to accept values from users.
• Understand why input values are received as strings.
• Convert input data to integer and float values.
• Perform calculations using user input.
• Develop simple interactive Python applications.

Learning Outcomes

• Create Python programs that accept user input.
• Convert user input into suitable data types.
• Calculate totals, averages, areas, fees, and results.
• Display clear and professional output messages.

4.3 Output Operation using print()

Output means showing information on the screen. In Python, the print() function is used to display output.

Example

print("Welcome to Python Programming")
print("Perak Digital Transformation Centre")
print("Chapter 4: Input and Output Operations")

4.4 Displaying Variables with print()

The print() function can also display values stored in variables.

student_name = "Amin"
course_name = "Certified Python Programmer"
training_centre = "PDTC"

print("Student Name:", student_name)
print("Course Name:", course_name)
print("Training Centre:", training_centre)

4.5 Formatting Output

Output should be clear and easy to understand. Python allows different ways to format output.

Using f-string

name = "Amin"
marks = 85

print(f"Student {name} scored {marks} marks.")

An f-string allows variables to be placed directly inside a message using curly brackets.

4.6 Input Operation using input()

Input means accepting data from the user. In Python, the input() function is used to take user input.

Example

student_name = input("Enter your name: ")

print("Welcome", student_name)

4.7 Input Values are Strings by Default

Even if the user enters a number, Python receives it as text when using input(). This is why data type conversion is required before calculation.

age = input("Enter your age: ")

print(type(age))

4.8 Data Type Conversion while Taking Input

Type conversion changes input data from string to another data type such as integer or float.

Integer Input Example

age = int(input("Enter your age: "))

print("Your age is:", age)
print(type(age))

Float Input Example

course_fee = float(input("Enter course fee: "))

print("Course Fee:", course_fee)
print(type(course_fee))

4.9 Calculating Using User Input

After converting input values into numbers, Python can perform calculations.

Add Two Numbers

number1 = int(input("Enter first number: "))
number2 = int(input("Enter second number: "))

total = number1 + number2

print("Total:", total)

4.10 Average Marks Calculator

This program accepts three subject marks, calculates total marks and average marks, and displays the result.

python_marks = float(input("Enter Python marks: "))
database_marks = float(input("Enter Database marks: "))
web_marks = float(input("Enter Web Development marks: "))

total_marks = python_marks + database_marks + web_marks
average_marks = total_marks / 3

print("Total Marks:", total_marks)
print("Average Marks:", average_marks)

4.11 Course Fee Calculator

This example shows how user input can be used in a training centre fee calculation system.

course_fee = float(input("Enter course fee: "))
discount = float(input("Enter discount amount: "))
registration_fee = float(input("Enter registration fee: "))

final_amount = course_fee - discount + registration_fee

print("Course Fee: RM", course_fee)
print("Discount: RM", discount)
print("Registration Fee: RM", registration_fee)
print("Final Amount Payable: RM", final_amount)

4.12 Developing Interactive Python Applications

An interactive Python application accepts user input, processes the input, and provides output based on the user’s data.

Interactive Student Profile Application

name = input("Enter student name: ")
age = int(input("Enter student age: "))
course = input("Enter course name: ")
marks = float(input("Enter final marks: "))

print("----- Student Profile -----")
print("Name:", name)
print("Age:", age)
print("Course:", course)
print("Final Marks:", marks)

4.13 Interactive Certificate Eligibility App

This application checks whether a student is eligible for a certificate based on marks and attendance.

student_name = input("Enter student name: ")
marks = float(input("Enter marks: "))
attendance = float(input("Enter attendance percentage: "))

eligible = marks >= 50 and attendance >= 80

print("Student Name:", student_name)
print("Certificate Eligibility:", eligible)

4.14 Common Beginner Mistakes

4.15 Hands-On Practice

birth_year = int(input("Enter your birth year: "))
current_year = 2026

age = current_year - birth_year

print("Your age is approximately:", age)

4.16 Final Assessment Quiz

Answer the following questions. Correct Answer = +1 Mark Wrong Answer = -0.5 Mark

Final Practical Assessment

Develop an interactive Python program named training_fee_calculator.py. The program must ask for student name, course name, course fee, discount amount, and registration fee. It must calculate and display the final amount payable using proper data type conversion.

4.17 Chapter Summary

In this chapter, learners studied how Python programs communicate with users using input and output operations. Learners practiced using print(), input(), int(), and float() to build interactive Python applications.