April Python Bootcamp Day 4

 

Day 4: Input & Output in Python

Making Your Programs Interactive 

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 Introduction

Till now, your programs were static — they always produced the same output.

But real-world programs don’t work like that.

They take input from users, process it, and then show output.

 This is the core idea of programming:

Input → Processing → Output

In this blog, you’ll learn how to:

• Take input from users
• Display output properly
• Format output professionally

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 What is Input?

Input is data provided to a program during execution.

This data can come from:

• Keyboard (user typing)
• Files
• APIs (advanced)

But for now, we focus on user input from keyboard.

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 Why Input is Important?

Without input:

• Programs are fixed
• No flexibility
• Same output every time

Example:

 Static Program:

print("Hello Piyush")

 Dynamic Program:

name = input("Enter your name: ")
print("Hello", name)

 Now the output changes based on user → interactive program

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 Taking Input in Python

Python provides a built-in function:

input()

 Basic Example:

name = input("Enter your name: ")
print(name)

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 Important Concept (VERY IMPORTANT)

input() always returns a string

age = input("Enter your age: ")
print(type(age))   # Output: <class 'str'>

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 Type Conversion (Revision)

To perform calculations, convert input:

age = int(input("Enter age: "))
print(age + 5)

Common Conversions:

int(input())     # integer
float(input())   # decimal
str(input())     # string (default)

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 What is Output?

Output is the result displayed to the user after processing input.

Without output:

• User cannot see results
• Program has no visible effect

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 Displaying Output in Python

Python uses:

print()

 Basic Example:

print("Hello World")

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 Printing Multiple Values

name = "Piyush"
age = 21

print("Name:", name, "Age:", age)

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 sep and end (Advanced Printing)

 Separator (sep)

print("Python", "Java", "C++", sep=" | ")

 End Parameter (end)

print("Hello", end=" ")
print("World")

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 String Formatting

String formatting helps display output in a clean and professional way.

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 1. f-Strings (Recommended)

name = "Piyush"
age = 21

print(f"My name is {name} and I am {age} years old")

 Fast, readable, modern

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 2. .format() Method

print("My name is {} and I am {}".format(name, age))

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 3. % Formatting (Old Style)

print("My name is %s and age is %d" % (name, age))

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 Escape Characters

print("Hello\nWorld")   # New line
print("Hello\tWorld")   # Tab
print("He said \"Hi\"")

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 Practice Questions

 Basic

Take name as input and print:
"Welcome, <name>"

Take two numbers and print their sum

Take age and print:
"You will be <age+5> after 5 years"

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 Intermediate

Take name and marks, print:
"<name> scored <marks> marks"

Take 3 numbers and print their average

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 Tricky

a = input("Enter number: ")
b = input("Enter number: ")
print(a + b)

 Why is output concatenation and not addition?

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print("Hello", end="---")
print("World", end="***")

 Predict output

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a, b = input().split()
print(int(a) + int(b))

 What if user enters only one value?