Input, Output & Comments

✕

1. Output using print()

    1.1 What is print()?
    1. print() is a built-in function used to display output on the screen. We can use print() to display: 📝 Text 🔢 Numbers 📦 Variables 🧮 Expressions Examples: print("Hello") # ➜ Hello print(5 + 2) # ➜ 7 name = "Rabindra" print(name) # ➜ Rabindra age = 30 print("I am", age, "years old") # ➜ I am 30 years old
    1.2 Printing Text
    1. Text must be written inside quotes. Example:print("Hello, World!") Output: Hello, World!
    1.3 Printing Numbers and Expressions
    1. Numbers and expressions can be printed directly. Example: print(25) print(5 + 2) print(10 * 3)Output: 25 7 30
    1.4 Printing Variables
    1. We can store a value in a variable and print it later. Example: name = "Rabindra" age = 30print(name) print(age)Output: Rabindra 30
    1.5 Printing Multiple Values
    1. We can print multiple values by separating them with commas. Example: name = "Rabindra" age = 30print("My name is", name) print("I am", age, "years old")Output: My name is Rabindra I am 30 years old 📌 When we use commas inside print(), Python automatically adds spaces between values.

2. f-strings

    2.1 What are f-strings?
    1. Imagine a form letter with blanks: Dear ___, your order of ___ will arrive on ___. If we have values stored in variables, f-strings help us fill those blanks automatically. Example name = "Ram" item = "book" date = "Monday"print(f"Dear {name}, your order of {item} will arrive on {date}.")Output: Dear Ram, your order of book will arrive on Monday. f-strings are used to create formatted output by placing variables or expressions directly inside a string. Syntax:f"Text {variable}" 📌 We must write f before the string. 📌 Variables or expressions are written inside curly braces { }.
    2.2 Why use f-strings?
    1. Without f-string: name = "Rabindra" age = 30print("My name is", name, "and I am", age, "years old.")Output: My name is Rabindra and I am 30 years old. Using f-string: print(f"My name is {name} and I am {age} years old.")Output: My name is Rabindra and I am 30 years old. ✅ f-strings make the output cleaner and easier to understand.
    2.3 Using Expressions inside f-strings
    1. We can also write expressions inside curly braces. Example: age = 30 print(f"Next year, I will be {age + 1} years old.")Output: Next year, I will be 31 years old.

3. Format Specifiers

    3.1 What are Format Specifiers?
    1. A format specifier is a short instruction that tells Python exactly how we want a value to look. It is similar to choosing formatting options in Word, such as alignment, spacing, or decimal places. Format specifiers are used inside f-strings to customize output. They help us control: 📏 Width 🎯 Decimal places ↔️ Alignment ✨ Padding characters Syntax:f"{variable:format_specifier}"
    3.2 🎯 Decimal Formatting
    1. We can control the number of digits after decimal point. Example: num = 3.14159 print(f"{num:.2f}")Output: 3.14 Here, .2f means display the number with 2 digits after decimal point.
    3.3 📏 Width Formatting
    1. Width means the minimum space given to display a value. Example: num = 123 print(f"{num:10}")Output: 123 Here, width 10 means Python uses 10 spaces to display the value.
    3.4 ↔️ Alignment
    1. We can align values using: < ➜ Left align > ➜ Right align ^ ➜ Center align Example: item = "Apple"print(f"{item:<10}") # Left aligned print(f"{item:>10}") # Right aligned print(f"{item:^10}") # Center aligned
    3.5 ✨ Fill Character
    1. We can fill empty spaces with a character. Example: num = 123print(f"{num:->10}") # ➜ -------123 print(f"{num:-<10}") # ➜ 123------- print(f"{num:#^11}") # ➜ ####123####
    3.6 Format Specifier Breakdown
    1. Example: print(f"{num:->10}") Here: - ➜ Fill character > ➜ Right alignment 10 ➜ Width Example: print(f"{num:.2f}") Here: .2 ➜ Two digits after decimal f ➜ Floating-point number
    3.7 Table-like Output Example
    1. item_1 = "Apple" price_1 = 3item_2 = "Banana" price_2 = 10item_3 = "Orange" price_3 = 200print(f"{'Item':<12}{'Price':>5}") print("-" * 17) print(f"{item_1:<12}{price_1:>5}") print(f"{item_2:<12}{price_2:>5}") print(f"{item_3:<12}{price_3:>5}")Output: Item Price ----------------- Apple 3 Banana 10 Orange 200
3.8 Format Specifier Summary
SpecifierDescription
FillCharacter used for padding the output (default is space). Has to be single character
AlignAlignment of the output: < for left, > for right, ^ for center. Default: > for numbers and < for strings
WidthMinimum width of the output
PrecisionNumber of digits after decimal point for floating-point numbers
Format Specifier Summary Table

4. User Input

    4.1 ⌨️ What is input()?
    1. input() is used to take input from the user. Example: name = input("Enter your name: ") print(f"Hello, {name}!") If user enters Rabindra, output will be: Hello, Rabindra!
    4.2 ⌨️ input() Always Returns String
    1. input() always returns data as a string. Example: num_1 = input("Enter first number: ") num_2 = input("Enter second number: ")print(num_1 + num_2) If user enters: 10 5 Output: 105 😕 Why did Python show 105 instead of 15? This happened because input() returns values as strings. So Python joined "10" and "5" as text.
    4.3 ⌨️ Type Conversion with input()
    1. To perform mathematical operations, we need to convert input into number. Example: num_1 = int(input("Enter first number: ")) num_2 = int(input("Enter second number: "))total = num_1 + num_2 print(f"Sum = {total}") If user enters: 10 5 Output: Sum = 15
    4.4 ⌨️ Taking Float Input
    1. If the input can contain decimal value, use float(). Example: price = float(input("Enter price: ")) print(f"Price = Rs. {price:.2f}")
    4.5 ⌨️ Input and Calculation Example
    1. length_in_cm = float(input("Enter length in cm: ")) length_in_m = length_in_cm / 100 print(f"Length = {length_in_m:.2f} m")

5. Comments

    5.1 What are Comments?
    1. Comments are notes written inside code. They are not executed by Python. Comments are used to: 📝 Explain code 📌 Improve readability 🧠 Help us remember logic
    5.2 Single-line Comments
    1. Single-line comments start with #. Example: # This program displays a greeting messagename = "Rabindra" print(f"Hello, {name}!")
    5.3 Inline Comments
    1. Comments can also be written beside code. Example: age = 30 # stores age of user print(age)
    5.4 Block Notes using Triple Quotes
    1. Python does not have a separate multi-line comment symbol like some other languages. However, triple quotes can be used to write multi-line notes when they are not assigned to a variable. Example: """ This program takes user information and displays it in a formatted way. """name = "Rabindra" print(name) 📌 Triple quotes actually create multi-line strings, but beginners often use them as block notes.
    5.5 Comment Shortcut in VS Code
    1. In VS Code, we can use: Ctrl + / to comment or uncomment selected lines.

Practice QuestionsNot started

  1. 1. Output and f-strings

    Question 1 of 5

      1.1 Practice output and f-string formatting:
      1. Create a variable name and display: Hello, {name}!
      2. Create variables name and age. Display output in this format: My name is Python and I am 30 years old.
      3. Create variables item and price. Display output in this format: Ram bought a pen for Rs. 10.56.
      4. Create variable age. Display what the age will be next year using an f-string.

  2. 2. Format Specifiers

    Question 2 of 5

      2.1 Practice format specifier tasks:
      1. Create a variable num = 3.14159 and display it up to 2 decimal places.
      2. Create a variable price = 125.5 and display it in this format: Price: Rs. 125.50
      3. Create a variable num = 123 and display it with width 10.
      4. Create a variable num = 123 and display it in these formats: -------123 123------- ####123####
      5. Create item and price variables and display them in table-like format: Item Price ----------------- Apple 3 Banana 10 Orange 200

  3. 3. User Input

    Question 3 of 5

      3.1 Practice tasks using input():
      1. Ask user for his/her name and display: Hello, <name>!
      2. Ask user for birth year and current year. Calculate and display his/her age.
      3. Ask user for length in feet. Convert and display its value in meter. Formula: 1 ft = 0.3048 m
      4. Ask user for two numbers and display their: Sum, Difference, Product, Quotient. Note: Output should be in proper human-readable format, not just numbers.
      5. Ask user for length in cm. Convert it into meter and display the result up to 2 decimal places.

  4. 4. Input, Calculation, and Formatting

    Question 4 of 5

      4.1 Practice combined input, calculation, and formatting tasks:
      1. Ask user for name and price of a pen. Display output in this format: Ram bought a pen for Rs. 10.56.
      2. Ask user for current year, month, and day. Display it in this format: Today's Date: 2026-03-12
      3. Ask user for name and marks in 3 subjects. Calculate average percentage and display: Hari scored 85.5% in exam.
      4. Ask user for mass and length of a cube. Calculate and display its density. Formula: density = mass / volume, volume = length ** 3
      5. Ask user for a file name in format file.ext. Extract and display the file extension.

  5. 5. Comments

    Question 5 of 5

      5.1 Practice using comments in code:
      1. Write a program that displays your name and age. Add a comment explaining what the program does.
      2. Write a program that calculates area of a rectangle. Add comments explaining length, breadth, and area.
      3. Write a program that converts feet to meter. Add comments explaining the formula.
      4. Write a program with at least three lines of code and use Ctrl + / in VS Code to comment and uncomment them.