Input and Output Functions

Introduction

Programs become truly interactive when they can accept data from the user and display results back. In Python, this is done using two built-in functions: input() for taking input, and print() for displaying output.

The print() Function

The print() function displays output on the screen. It can take one or more values, separated by commas.

print("Hello, World!")
print("Sum is:", 15)

sep and end Parameters

By default, print() separates multiple values with a space (sep=" ") and ends with a newline (end="\n"). Both can be customized.

print("a", "b", "c", sep="-")      # a-b-c
print("Hello", end=" ")
print("World")                # Hello World (same line)

The input() Function

The input() function pauses the program and waits for the user to type something, then returns it — always as a string.

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

Taking Numeric Input

Since input() always returns a string, you must convert it using int() or float() before doing math with it.

age = int(input("Enter your age: "))
print("Next year you'll be", age + 1)

Formatting Output (f-strings)

Python's f-strings (formatted string literals) let you embed variables and expressions directly inside a string, prefixed with f.

name = "Riya"
age = 21

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

Output: My name is Riya and I am 21 years old.

Real-Life Example: Simple Calculator

num1 = float(input("Enter first number: "))
num2 = float(input("Enter second number: "))

result = num1 + num2

print(f"The sum of {num1} and {num2} is {result}")

Common Beginner Mistakes

Quick Revision

Summary

The input() and print() functions are the bridge between your program and its user. With input() you can accept data (always as a string), and with print() — along with f-strings for clean formatting — you can display results clearly. With this, you've completed the foundational building blocks of Python covered in Unit 1.