Input & Output

Learn how to get user input and display formatted output in Python

The input() Function

input() reads user input as a string
Always returns a string, even if user enters numbers
Can display a prompt message to the user
Use type casting to convert input to other types

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

# Input with type conversion
age = int(input("Enter your age: "))
print(f"Next year you will be {age + 1}")

# Multiple inputs
x = input("Enter first number: ")
y = input("Enter second number: ")
total = int(x) + int(y)
print(f"Sum: {total}")

The print() Function

print() displays output to the console
Can print multiple values separated by commas
Default separator is space, can be changed with sep parameter
Default end character is newline, can be changed with end parameter

# Basic print
print("Hello World")

# Multiple values
print("Python", "is", "awesome")

# Custom separator
print("apple", "banana", "cherry", sep=", ")

# Custom end character
print("Loading", end="...")
print("Done!")

String Formatting

f-strings (formatted string literals) - modern and recommended
.format() method - older but still widely used
% formatting - legacy style, rarely used now
f-strings support expressions inside curly braces

name = "Alice"
age = 25
score = 95.5

# f-strings (Python 3.6+)
print(f"Name: {name}, Age: {age}")
print(f"Score: {score:.1f}%")
print(f"Next year: {age + 1}")

# .format() method
print("Name: {}, Age: {}".format(name, age))
print("Name: {0}, Age: {1}".format(name, age))

# % formatting (old style)
print("Name: %s, Age: %d" % (name, age))

Advanced Formatting

Alignment and padding with f-strings
Number formatting (decimals, thousands separator)
Date and time formatting
Multi-line strings with triple quotes

# Alignment
text = "Python"
print(f"{text:>10}")  # Right align
print(f"{text:<10}")  # Left align
print(f"{text:^10}")  # Center align

# Number formatting
pi = 3.14159
print(f"{pi:.2f}")  # 2 decimal places
big_num = 1000000
print(f"{big_num:,}")  # Thousands separator

# Multi-line output
message = """
Welcome to Python!
This is a multi-line string.
Enjoy learning!
"""
print(message)