Tutorial 8: Outputting Data (`print()`)

Learning Objective

To be able to write correct statements using print

1. Introduction

1.1 Purpose of print()

The print() function is Python's primary tool for displaying information to the console (standard output). It converts the objects you pass to it into strings and writes them to the output stream, typically your terminal or command prompt.

Why is this important?

It's how you communicate results to the user.
It's essential for debugging – you can print variable values to see what your program is doing.
It allows you to format output in a readable and user‑friendly way.

Under the Hood:

print() automatically calls str() on each argument to convert it to a string.
It writes to sys.stdout, which is the standard output stream.

1.2 Basic Usage – Printing Values

Printing a single value:

print(42)              # Outputs: 42
print("Hello")         # Outputs: Hello
print(3.14159)         # Outputs: 3.14159
print(True)            # Outputs: True
print([1, 2, 3])       # Outputs: [1, 2, 3]

Printing multiple values:

print("Hello", "World", 2026)
# Outputs: Hello World 2026

When you pass multiple arguments, print() automatically inserts a space between them.

Multiple types in one print():

name = "Alice"
age = 30
score = 95.5
print("Name:", name, "Age:", age, "Score:", score)
# Outputs: Name: Alice Age: 30 Score: 95.5

Important: print() can accept any number of arguments. Each argument is converted to a string and printed with separators.

1.3 The sep Parameter – Controlling Separators

The sep (separator) parameter specifies what string is placed between multiple arguments. By default, sep is a single space ' '.

Syntax:

print(value1, value2, ..., sep='separator_string')

Examples:

# Default separator (space)
print("A", "B", "C")              # A B C

# Comma and space
print("A", "B", "C", sep=", ")    # A, B, C

# No separator
print("A", "B", "C", sep="")      # ABC

# Custom separator
print("A", "B", "C", sep="-*-")   # A-*-B-*-C

# Newline separator
print("A", "B", "C", sep="\n")    # A (newline) B (newline) C

Use Case – Creating CSV (Comma-Separated Values):

print("Name", "Age", "City", sep=",")  # Name,Age,City

Use Case – Building a Path:

print("folder", "subfolder", "file.txt", sep="/")  # folder/subfolder/file.txt

1.4 The end Parameter – Controlling the Ending

The end parameter specifies what string is printed at the end of the print() call. By default, end is a newline character '\n', which moves the cursor to the next line.

Syntax:

print(value1, value2, ..., end='ending_string')

Examples:

# Default (newline)
print("Hello")
print("World")
# Outputs:
# Hello
# World

# No newline (print on same line)
print("Hello", end=" ")
print("World")
# Outputs: Hello World

# Custom ending
print("Hello", end="!!!")
print("World")
# Outputs: Hello!!!World

# Empty ending
print("Hello", end="")
print("World")
# Outputs: HelloWorld

Use Case – Building a Progress Indicator:

import time
for i in range(5):
    print(".", end="", flush=True)  # flush=True forces immediate output
    time.sleep(0.5)
print(" Done!")
# Outputs: ..... Done! (with delays between dots)

Use Case – Printing in a Loop Without Newlines:

for i in range(1, 6):
    print(i, end=" ")
# Outputs: 1 2 3 4 5

Use Case – Creating a Table Row:

print("Row 1", end=" | ")
print("Column A", end=" | ")
print("Column B")
# Outputs: Row 1 | Column A | Column B

1.5 Combining sep and end

You can use both parameters simultaneously:

print("A", "B", "C", sep=", ", end=".\n")
# Outputs: A, B, C.
# (then a newline)

Example – Building a Sentence:

words = ["The", "quick", "brown", "fox"]
for word in words:
    print(word, end=" ")
print("jumps over the lazy dog.")
# Outputs: The quick brown fox jumps over the lazy dog.

1.6 The file Parameter – Writing to a File

print() can also write to a file instead of the console. This is done using the file parameter.

Syntax:

print("Hello", file=file_object)

Example:

with open("output.txt", "w") as f:
    print("Hello, World!", file=f)
    print("This is line 2.", file=f)
# This writes to output.txt instead of the console.

Note: This is an advanced topic; for this unit, the focus is on console output.

1.7 String Formatting – Making Output Look Professional

While you can use + for concatenation, it gets messy quickly. Python provides better ways to embed variables in strings.

1.7.1 f‑strings (Formatted String Literals) – RECOMMENDED (Python 3.6+)

Prefix the string with f or F. Inside curly braces {}, you can put any Python expression (variable names, arithmetic, function calls, etc.).

Basic Usage:

name = "Alice"
age = 30
print(f"Hello, {name}! You are {age} years old.")
# Outputs: Hello, Alice! You are 30 years old.

Expressions Inside f‑strings:

price = 19.99
quantity = 3
print(f"Total: ${price * quantity:.2f}")
# Outputs: Total: $59.97

Calling Functions:

name = "python"
print(f"Uppercase: {name.upper()}")
# Outputs: Uppercase: PYTHON

Formatting Numbers (Important):

Format Specifier	Meaning	Example	Output
`{value:.2f}`	2 decimal places	`{3.14159:.2f}`	`3.14`
`{value:.0f}`	No decimals (rounds)	`{3.7:.0f}`	`4`
`{value:,}`	Comma as thousands separator	`{1234567:,}`	`1,234,567`
`{value:,.2f}`	Thousands + 2 decimals	`{1234567.891:,}`	`1,234,567.89`
`{value:>10}`	Right‑align in 10 spaces	`{"abc":>10}`	`abc`
`{value:<10}`	Left‑align in 10 spaces	`{"abc":<10}`	`abc`
`{value:^10}`	Center in 10 spaces	`{"abc":^10}`	`abc`
`{value:.3%}`	Percentage with 3 decimals	`{0.1234:.3%}`	`12.340%`
`{value:b}`	Binary representation	`{10:b}`	`1010`
`{value:x}`	Hexadecimal	`{255:x}`	`ff`

Examples:

salary = 75000.50
print(f"Salary: ${salary:,.2f}")   # Salary: $75,000.50

percentage = 0.8576
print(f"Pass rate: {percentage:.1%}")  # Pass rate: 85.8%

name = "Bob"
print(f"{name:>10}")   # "        Bob"
print(f"{name:<10}")   # "Bob        "

1.7.2 The .format() Method (Older but Still Common)

Before f‑strings, this was the recommended method.

Basic Usage:

name = "Alice"
age = 30
print("Hello, {}! You are {} years old.".format(name, age))
# Outputs: Hello, Alice! You are 30 years old.

Positional Arguments:

print("{1} is {0} years old.".format(30, "Alice"))
# Outputs: Alice is 30 years old.

Named Arguments:

print("Hello, {name}! You are {age} years old.".format(name="Alice", age=30))

Number Formatting:

print("Total: {:.2f}".format(19.99 * 3))  # Total: 59.97
print("Salary: {:,}".format(75000))       # Salary: 75,000

1.7.3 Old‑Style % Formatting (Legacy)

Older than .format(), inspired by C's printf.

Examples:

name = "Alice"
age = 30
print("Hello, %s! You are %d years old." % (name, age))
# Outputs: Hello, Alice! You are 30 years old.

Common Placeholders:

%s – string
%d – integer
%f – float
%.2f – float with 2 decimals

Note: f‑strings are recommended for new code. This method is kept for legacy code.

1.8 Escape Sequences – Special Characters in Strings

Escape sequences allow you to insert special characters into strings. They start with a backslash \.

Escape Sequence	Description	Example	Output
`\n`	Newline	`print("A\nB")`	`A` (newline) `B`
`\t`	Tab	`print("A\tB")`	`A B`
`\\`	Backslash	`print("C:\\path")`	`C:\path`
`\"`	Double quote	`print("She said \"Hi\"")`	`She said "Hi"`
`\'`	Single quote	`print('It\'s nice')`	`It's nice`
`\r`	Carriage return	`print("Hello\rWorld")`	`World` (overwrites)
`\b`	Backspace	`print("Hello\bWorld")`	`HellWorld`

Examples:

print("Line 1\nLine 2\nLine 3")
# Outputs:
# Line 1
# Line 2
# Line 3

print("Name\tAge\tCity")
print("Alice\t30\tNYC")
print("Bob\t25\tLA")
# Outputs a simple table with tabs

1.9 Combining print() with input() – Interactive Programs

Here's a complete interactive program using both:

name = input("Enter your name: ").strip()
age = input("Enter your age: ")

try:
    age = int(age)
    print(f"Hello, {name}! Next year you will be {age + 1}.")
except ValueError:
    print("Invalid age. Please enter a number.")

1.10 Common Pitfalls and Best Practices

Pitfall 1: Forgetting to Convert Types:

age = 30
print("Age: " + age)  # TypeError!
# Correct:
print("Age: " + str(age))
# Or better:
print(f"Age: {age}")

Pitfall 2: Using print() in Production Code:

For debugging, use print(), but remove or replace with logging for production.
Excessive print() statements can slow down your program.

Pitfall 3: Missing Newlines:

print("Loading", end="")
# User sees "Loading" without a newline, which can be confusing.
# Better to show progress with a dot:
for i in range(5):
    print(".", end="", flush=True)
    time.sleep(0.5)
print(" Done!")

Best Practices:

Use f‑strings for most formatting – they're readable and fast.
Use sep and end for clean output, especially in loops.
Provide clear messages – tell the user what they're seeing.
Use \n for readability in long output.
Avoid string concatenation (+) when you have many variables – use f‑strings.

2. Code Examples (Annotated)

# --- Basic Print ---
print("--- Basic Print ---")
print(42)
print("Hello")
print(3.14159)
print([1, 2, 3])

# --- Multiple Arguments ---
print("\n--- Multiple Arguments ---")
print("Hello", "World", 2026)
print("Name:", "Alice", "Age:", 30)

# --- The sep Parameter ---
print("\n--- sep Parameter ---")
print("A", "B", "C", sep=", ")  # A, B, C
print("A", "B", "C", sep="")    # ABC
print("A", "B", "C", sep="|")   # A|B|C
print("A", "B", "C", sep="\n")  # A (newline) B (newline) C

# --- The end Parameter ---
print("\n--- end Parameter ---")
print("Hello", end=" ")
print("World")                   # Hello World

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

print("1", end="")
print("2", end="")
print("3")                       # 123

# --- Combining sep and end ---
print("\n--- Combining Parameters ---")
print("A", "B", "C", sep=", ", end=".\n")  # A, B, C.

# --- f-strings ---
print("\n--- f-strings ---")
name = "Alice"
age = 30
price = 19.99
quantity = 3
salary = 75000.50
percentage = 0.8576

print(f"Hello, {name}! You are {age} years old.")
print(f"Total: ${price * quantity:.2f}")
print(f"Salary: ${salary:,.2f}")
print(f"Pass rate: {percentage:.1%}")
print(f"{name:>10}")   # Right-aligned
print(f"{name:<10}")   # Left-aligned

# --- Escape Sequences ---
print("\n--- Escape Sequences ---")
print("Line 1\nLine 2\nLine 3")
print("Name\tAge\tCity")
print("Alice\t30\tNYC")
print("C:\\Users\\Alice")
print("She said \"Hello!\"")

# --- Realistic Example: Shopping Receipt ---
print("\n--- Shopping Receipt ---")
item = "Laptop"
unit_price = 1299.99
quantity = 2
tax_rate = 0.08

subtotal = unit_price * quantity
tax = subtotal * tax_rate
total = subtotal + tax

print("=" * 40)
print(f"{'ITEM':<20}{'QTY':>5}{'PRICE':>10}")
print("-" * 40)
print(f"{item:<20}{quantity:>5}${unit_price:>9,.2f}")
print("-" * 40)
print(f"{'Subtotal:':>30} ${subtotal:>9,.2f}")
print(f"{'Tax (8%):':>30} ${tax:>9,.2f}")
print(f"{'Total:':>30} ${total:>9,.2f}")
print("=" * 40)

3. Quiz (Check Your Understanding)

Question 1: What is the output of print("Hello", "World")?
a) HelloWorld
b) Hello World
c) Hello,World
d) Hello\nWorld

Answer

b) `Hello World`

Question 2: What is the output of print("A", "B", "C", sep=", ")?
a) A,B,C
b) A B C
c) A, B, C
d) A-B-C

Answer

c) `A, B, C`

Question 3: What is the output of print("Hello", end=" "); print("World")?
a) Hello World
b) HelloWorld
c) Hello\nWorld
d) Hello World (with newline after)

Answer

a) `Hello World` (on the same line)

Question 4: What is the output of print(f"Total: {3 * 4}")?
a) Total: 12
b) Total: 3 * 4
c) Total: 34
d) Total: 7

Answer

a) `Total: 12`

Question 5: What does \n represent?
a) Tab
b) Newline
c) Backslash
d) Space

Answer

b) Newline

Question 6: Which f‑string correctly formats a float to 2 decimal places?
a) {value:.2f}
b) {value:2f}
c) {value:.2}
d) {value:.2d}

Answer

a) `{value:.2f}`

Question 7: What is the output of print(f"{1234567:,}")?
a) 1234567
b) 1,234,567
c) 1234567,
d) 1.234.567

Answer

b) `1,234,567`

Question 8: What is the output of print("Hello", "World", sep="\n")?
a) Hello World
b) Hello\nWorld
c) Hello (newline) World
d) Hello,World

Answer

c) `Hello` and `World` on separate lines.

Question 9: What is the output of:

for i in range(3):
    print(i, end=" ")

a) 0 1 2
b) 0\n1\n2
c) 012
d) 0,1,2

Answer

a) `0 1 2`

Question 10: Which is the recommended way to format a string in modern Python?
a) % formatting
b) .format() method
c) f‑strings
d) String concatenation with +

Answer

c) f‑strings

4. Exercises (In-Class / Lab Practice)

Exercise 1: Basic Formatting
Create variables for name, age, height, weight; print a summary with appropriate formatting.

Sample Solution

```python name = "Alice" age = 30 height = 1.75 weight = 68.5 bmi = weight / (height ** 2) print(f"Name: {name}") print(f"Age: {age} years old") print(f"Height: {height:.2f} m") print(f"Weight: {weight:.1f} kg") print(f"BMI: {bmi:.1f}") ```

Exercise 2: Shopping Cart Output
Given items and quantities, print a formatted table.

Sample Solution

```python items = [("Apple", 0.50), ("Banana", 0.30), ("Orange", 0.80)] quantities = [3, 5, 2] total = 0 print("Item Qty Price Subtotal") for (item, price), qty in zip(items, quantities): subtotal = price * qty total += subtotal print(f"{item:<8}{qty:>3} ${price:>5.2f} ${subtotal:>6.2f}") print(f"Total: ${total:.2f}") ```

Exercise 3: Progress Bar
Print a progress indicator that updates on the same line.

Sample Solution

```python import time for i in range(1, 11): percent = i * 10 bar = '#' * i + '.' * (10 - i) print(f"\rProgress: [{bar}] {percent}%", end="") time.sleep(0.5) print() ```

Exercise 4: Multiplication Table

Write a program that:

Asks the user for a number.
Prints the multiplication table from 1 to 10 in a formatted grid:
```
1 x 5 = 5
2 x 5 = 10
...
10 x 5 = 50
```
Use f‑strings with alignment to line up the equals signs.

Sample Answer

"""
MULTIPLICATION TABLE
Demonstrates formatted output with f-strings and alignment
"""

print("=" * 60)
print("MULTIPLICATION TABLE GENERATOR")
print("=" * 60)

# --- Get user input ---
try:
    number = float(input("\nEnter a number: "))
except ValueError:
    print("❌ Invalid input! Using 5 as default.")
    number = 5

print(f"\nMultiplication Table for {number}")
print("-" * 40)

# --- Method 1: Simple version ---
print("\nMethod 1: Simple")
print("-" * 30)

for i in range(1, 11):
    result = i * number
    print(f"{i} x {number} = {result}")

# --- Method 2: Aligned version with f-strings ---
print("\nMethod 2: Aligned")
print("-" * 30)

for i in range(1, 11):
    result = i * number
    print(f"{i:>2} x {number:>5} = {result:>8}")

# --- Method 3: Fully formatted grid ---
print("\nMethod 3: Formatted Grid")
print("-" * 40)

print(f"{'Multiplier':<10} {'Number':<10} {'Result':<10}")
print("-" * 40)

for i in range(1, 11):
    result = i * number
    print(f"{i:<10} {number:<10} {result:<10.2f}")

# --- Method 4: Professional table with alignment ---
print("\nMethod 4: Professional Table")
print("=" * 50)

# Header
print(f"{'MULTIPLICATION TABLE FOR':^50}")
print(f"{number:^50}")
print("=" * 50)
print(f"{'Expression':<20} {'Result':>30}")
print("-" * 50)

# Rows with aligned equals signs
for i in range(1, 11):
    result = i * number
    # Using f-string with alignment
    expression = f"{i} × {number}"
    print(f"{expression:<20} = {result:>28.2f}")

print("=" * 50)

# --- Method 5: With number formatting for decimals ---
print("\nMethod 5: With Decimal Formatting")
print("-" * 50)

# Detect if number is a whole number
if number.is_integer():
    display_number = int(number)
else:
    display_number = number

for i in range(1, 11):
    result = i * number
    if result.is_integer():
        display_result = int(result)
    else:
        display_result = result
    
    # Align the equals sign
    print(f"{i:>2} × {display_number:<5} = {display_result}")

# --- Bonus: Complete multiplication table (1-10) ---
print("\n" + "=" * 60)
print("BONUS: COMPLETE MULTIPLICATION TABLE (1-10)")
print("=" * 60)

# Generate a full 10x10 table
print("\n" + " " * 4 + "|", end="")
for col in range(1, 11):
    print(f"{col:>4}", end="")
print()
print("-" * 45)

for row in range(1, 11):
    print(f"{row:>2} |", end="")
    for col in range(1, 11):
        print(f"{row * col:>4}", end="")
    print()

print("\n" + "=" * 60)
print("FORMATTING CODES USED:")
print("=" * 60)
print("  • `{var:<10}`  - Left align in 10 spaces")
print("  • `{var:>10}`  - Right align in 10 spaces")
print("  • `{var:^10}`  - Center in 10 spaces")
print("  • `{var:.2f}`  - Format as float with 2 decimals")
print("  • `{var:,.2f}` - Format with thousands separators")
print("  • `{var:<20}`  - Left align to line up equals signs")
print("  • `.is_integer()` - Check if float is a whole number")
print("=" * 60)

Sample Output:

============================================================
MULTIPLICATION TABLE GENERATOR
============================================================

Enter a number: 7

Multiplication Table for 7.0
----------------------------------------

Method 1: Simple
------------------------------
1 x 7.0 = 7.0
2 x 7.0 = 14.0
3 x 7.0 = 21.0
4 x 7.0 = 28.0
5 x 7.0 = 35.0
6 x 7.0 = 42.0
7 x 7.0 = 49.0
8 x 7.0 = 56.0
9 x 7.0 = 63.0
10 x 7.0 = 70.0

Method 2: Aligned
------------------------------
 1 x   7.0 =      7.0
 2 x   7.0 =     14.0
 3 x   7.0 =     21.0
 4 x   7.0 =     28.0
 5 x   7.0 =     35.0
 6 x   7.0 =     42.0
 7 x   7.0 =     49.0
 8 x   7.0 =     56.0
 9 x   7.0 =     63.0
10 x   7.0 =     70.0

Method 3: Formatted Grid
----------------------------------------
Multiplier Number     Result
----------------------------------------
1          7          7.00      
2          7          14.00     
3          7          21.00     
4          7          28.00     
5          7          35.00     
6          7          42.00     
7          7          49.00     
8          7          56.00     
9          7          63.00     
10         7          70.00     

Method 4: Professional Table
==================================================
         MULTIPLICATION TABLE FOR         
                     7.0                   
==================================================
Expression                  Result
--------------------------------------------------
1 × 7.0                   =                7.00
2 × 7.0                   =               14.00
3 × 7.0                   =               21.00
4 × 7.0                   =               28.00
5 × 7.0                   =               35.00
6 × 7.0                   =               42.00
7 × 7.0                   =               49.00
8 × 7.0                   =               56.00
9 × 7.0                   =               63.00
10 × 7.0                  =               70.00
==================================================

Method 5: With Decimal Formatting
--------------------------------------------------
 1 × 7     = 7
 2 × 7     = 14
 3 × 7     = 21
 4 × 7     = 28
 5 × 7     = 35
 6 × 7     = 42
 7 × 7     = 49
 8 × 7     = 56
 9 × 7     = 63
10 × 7     = 70

============================================================
BONUS: COMPLETE MULTIPLICATION TABLE (1-10)
============================================================

    |   1   2   3   4   5   6   7   8   9  10
---------------------------------------------
 1 |   1   2   3   4   5   6   7   8   9  10
 2 |   2   4   6   8  10  12  14  16  18  20
 3 |   3   6   9  12  15  18  21  24  27  30
 4 |   4   8  12  16  20  24  28  32  36  40
 5 |   5  10  15  20  25  30  35  40  45  50
 6 |   6  12  18  24  30  36  42  48  54  60
 7 |   7  14  21  28  35  42  49  56  63  70
 8 |   8  16  24  32  40  48  56  64  72  80
 9 |   9  18  27  36  45  54  63  72  81  90
10 |  10  20  30  40  50  60  70  80  90 100

============================================================
FORMATTING CODES USED:
============================================================
  • `{var:<10}`  - Left align in 10 spaces
  • `{var:>10}`  - Right align in 10 spaces
  • `{var:^10}`  - Center in 10 spaces
  • `{var:.2f}`  - Format as float with 2 decimals
  • `{var:,.2f}` - Format with thousands separators
  • `{var:<20}`  - Left align to line up equals signs
  • `.is_integer()` - Check if float is a whole number
============================================================

Explanation:

Formatting Codes Used:

Code	Description	Example
`{var:<10}`	Left align in 10 spaces	`"5 "`
`{var:>10}`	Right align in 10 spaces	`" 5"`
`{var:^10}`	Center in 10 spaces	`" 5 "`
`{var:.2f}`	Float with 2 decimals	`7.00`
`{var:,.2f}`	Thousands separators + 2 decimals	`1,234.56`

Key Concepts:

Alignment – Use <, >, or ^ to control text positioning.
Width – The number after the alignment specifies the field width.
Number Formatting – f for float, d for integer.
Integer Check – .is_integer() checks if a float is a whole number.

Alternative Compact Version:

# Simple one-liner approach
n = float(input("Enter number: "))
print('\n'.join(f'{i:>2} x {n:>5} = {i*n:>8.2f}' for i in range(1, 11)))

Exercise 5: Receipt Printer

Write a program that:

Asks the user for item name, quantity, and price.
Calculates subtotal, tax (8%), and total.

Prints a formatted receipt:

========================================
ITEM                 QTY       PRICE
----------------------------------------
Laptop                 2    $1,299.99
----------------------------------------
Subtotal:                     $2,599.98
Tax (8%):                       $208.00
Total:                        $2,807.98
========================================

Use proper alignment, thousands separators, and 2 decimal places.

Sample Answer

"""
RECEIPT PRINTER
Demonstrates formatted output with alignment, currency, and tax calculation
"""

print("=" * 60)
print("📄 RECEIPT PRINTER")
print("=" * 60)

print("\nWelcome! Please enter the item details.\n")

# --- Get user input ---
item_name = input("Item name: ").strip()
if not item_name:
    item_name = "Item"

try:
    quantity = int(input("Quantity: "))
    if quantity < 0:
        print("⚠️ Quantity cannot be negative. Using 1.")
        quantity = 1
except ValueError:
    print("⚠️ Invalid quantity. Using 1.")
    quantity = 1

try:
    price = float(input("Price per item: $"))
    if price < 0:
        print("⚠️ Price cannot be negative. Using $0.00.")
        price = 0.0
except ValueError:
    print("⚠️ Invalid price. Using $0.00.")
    price = 0.0

# --- Calculate totals ---
subtotal = quantity * price
tax_rate = 0.08
tax = subtotal * tax_rate
total = subtotal + tax

# --- Method 1: Simple receipt ---
print("\n" + "=" * 60)
print("METHOD 1: Simple Receipt")
print("=" * 60)

print("\n" + "=" * 40)
print("RECEIPT")
print("=" * 40)
print(f"Item:     {item_name}")
print(f"Qty:      {quantity}")
print(f"Price:    ${price:,.2f}")
print("-" * 40)
print(f"Subtotal: ${subtotal:,.2f}")
print(f"Tax (8%): ${tax:,.2f}")
print("=" * 40)
print(f"TOTAL:    ${total:,.2f}")
print("=" * 40)

# --- Method 2: Professional receipt ---
print("\n" + "=" * 60)
print("METHOD 2: Professional Receipt")
print("=" * 60)

# Define constants for formatting
LINE_WIDTH = 50

print("\n" + "=" * LINE_WIDTH)
print(f"{'RECEIPT':^{LINE_WIDTH}}")
print("=" * LINE_WIDTH)
print(f"{'ITEM':<30} {'QTY':>5} {'PRICE':>12}")
print("-" * LINE_WIDTH)

# Format the item line with alignment
print(f"{item_name:<30} {quantity:>5} ${price:>11,.2f}")
print("-" * LINE_WIDTH)

# Summary lines with right alignment
print(f"{'Subtotal:':>38} ${subtotal:>9,.2f}")
print(f"{'Tax (8%):':>38} ${tax:>9,.2f}")
print("=" * LINE_WIDTH)
print(f"{'TOTAL:':>38} ${total:>9,.2f}")
print("=" * LINE_WIDTH)

# --- Method 3: Multi-item receipt ---
print("\n" + "=" * 60)
print("METHOD 3: Multi-Item Receipt")
print("=" * 60)

# Allow multiple items
items = []
print("\nEnter multiple items (type 'done' when finished):\n")

while True:
    name = input("Item name (or 'done'): ").strip()
    if name.lower() == 'done':
        break
    
    try:
        qty = int(input("  Quantity: "))
        if qty < 0:
            qty = 0
    except ValueError:
        qty = 0
    
    try:
        p = float(input("  Price: $"))
        if p < 0:
            p = 0.0
    except ValueError:
        p = 0.0
    
    items.append({"name": name, "qty": qty, "price": p})
    print()

if items:
    # Calculate totals
    subtotal = sum(item["qty"] * item["price"] for item in items)
    tax = subtotal * 0.08
    total = subtotal + tax
    
    # Print receipt
    print("\n" + "=" * LINE_WIDTH)
    print(f"{'STORE RECEIPT':^{LINE_WIDTH}}")
    print("=" * LINE_WIDTH)
    print(f"{'ITEM':<30} {'QTY':>5} {'PRICE':>12}")
    print("-" * LINE_WIDTH)
    
    for item in items:
        item_total = item["qty"] * item["price"]
        print(f"{item['name']:<30} {item['qty']:>5} ${item['price']:>11,.2f}")
    
    print("-" * LINE_WIDTH)
    print(f"{'Subtotal:':>38} ${subtotal:>9,.2f}")
    print(f"{'Tax (8%):':>38} ${tax:>9,.2f}")
    print("=" * LINE_WIDTH)
    print(f"{'TOTAL:':>38} ${total:>9,.2f}")
    print("=" * LINE_WIDTH)
else:
    print("\nNo items entered. Receipt not printed.")

# --- Method 4: Receipt with date and time ---
print("\n" + "=" * 60)
print("METHOD 4: Full Receipt with Date/Time")
print("=" * 60)

from datetime import datetime

def print_full_receipt(items, store_name="My Store", tax_rate=0.08):
    """
    Prints a full receipt with header, items, totals, and footer.
    """
    LINE_WIDTH = 50
    
    # Calculate totals
    subtotal = sum(item["qty"] * item["price"] for item in items)
    tax = subtotal * tax_rate
    total = subtotal + tax
    
    # Current date and time
    now = datetime.now()
    date_str = now.strftime("%B %d, %Y")
    time_str = now.strftime("%I:%M %p")
    
    # Print receipt
    print("\n" + "=" * LINE_WIDTH)
    print(f"{store_name:^{LINE_WIDTH}}")
    print("-" * LINE_WIDTH)
    print(f"{'Date:':<30} {date_str}")
    print(f"{'Time:':<30} {time_str}")
    print("-" * LINE_WIDTH)
    
    print(f"{'ITEM':<30} {'QTY':>5} {'PRICE':>12}")
    print("-" * LINE_WIDTH)
    
    for item in items:
        print(f"{item['name']:<30} {item['qty']:>5} ${item['price']:>11,.2f}")
    
    print("-" * LINE_WIDTH)
    print(f"{'Subtotal:':>38} ${subtotal:>9,.2f}")
    print(f"{'Tax (8%):':>38} ${tax:>9,.2f}")
    print("=" * LINE_WIDTH)
    print(f"{'TOTAL:':>38} ${total:>9,.2f}")
    print("=" * LINE_WIDTH)
    
    # Payment footer
    print(f"{'Thank you for your business!':^{LINE_WIDTH}}")
    print("=" * LINE_WIDTH)

# Demo with sample data
sample_items = [
    {"name": "Laptop", "qty": 2, "price": 1299.99},
    {"name": "Mouse", "qty": 3, "price": 29.99},
    {"name": "Keyboard", "qty": 1, "price": 89.50}
]

print("\nSample Multi-Item Receipt:")
print_full_receipt(sample_items, "TECH STORE", 0.08)

# --- Single Item Full Receipt ---
print("\n" + "=" * 60)
print("FULL RECEIPT (Single Item)")
print("=" * 60)

# Recreate the exact receipt from the exercise
single_item = [{"name": "Laptop", "qty": 2, "price": 1299.99}]
print_full_receipt(single_item, "TECH STORE", 0.08)

print("\n" + "=" * 60)
print("KEY TAKEAWAYS")
print("=" * 60)
print("  • `{var:>10}` - Right align in 10 spaces")
print("  • `{var:^10}` - Center in 10 spaces")
print("  • `{var:<10}` - Left align in 10 spaces")
print("  • `{var:,.2f}` - Thousands separator with 2 decimals")
print("  • Use `$` prefix for currency formatting")
print("  • `datetime` module for date/time display")
print("  • Tax = subtotal × tax_rate")
print("  • Total = subtotal + tax")
print("=" * 60)

Sample Output:

============================================================
📄 RECEIPT PRINTER
============================================================

Welcome! Please enter the item details.

Item name: Laptop
Quantity: 2
Price per item: $1299.99

============================================================
METHOD 1: Simple Receipt
============================================================

========================================
RECEIPT
========================================
Item:     Laptop
Qty:      2
Price:    $1,299.99
----------------------------------------
Subtotal: $2,599.98
Tax (8%): $208.00
========================================
TOTAL:    $2,807.98
========================================

============================================================
METHOD 2: Professional Receipt
============================================================

==================================================
                    RECEIPT                     
==================================================
ITEM                             QTY        PRICE
--------------------------------------------------
Laptop                            2   $1,299.99
--------------------------------------------------
                             Subtotal: $2,599.98
                            Tax (8%):   $208.00
==================================================
                              TOTAL: $2,807.98
==================================================

============================================================
METHOD 3: Multi-Item Receipt
============================================================

Enter multiple items (type 'done' when finished):

Item name (or 'done'): Laptop
  Quantity: 2
  Price: $1299.99

Item name (or 'done'): Mouse
  Quantity: 3
  Price: $29.99

Item name (or 'done'): Keyboard
  Quantity: 1
  Price: $89.50

Item name (or 'done'): done

==================================================
                  STORE RECEIPT                   
==================================================
ITEM                             QTY        PRICE
--------------------------------------------------
Laptop                            2   $1,299.99
Mouse                             3      $29.99
Keyboard                          1      $89.50
--------------------------------------------------
                             Subtotal: $2,719.96
                            Tax (8%):   $217.60
==================================================
                              TOTAL: $2,937.56
==================================================

============================================================
METHOD 4: Full Receipt with Date/Time
============================================================

Sample Multi-Item Receipt:

==================================================
                  TECH STORE                   
--------------------------------------------------
Date:                         August 14, 2026
Time:                          02:30 PM
--------------------------------------------------
ITEM                             QTY        PRICE
--------------------------------------------------
Laptop                            2   $1,299.99
Mouse                             3      $29.99
Keyboard                          1      $89.50
--------------------------------------------------
                             Subtotal: $2,719.96
                            Tax (8%):   $217.60
==================================================
                              TOTAL: $2,937.56
==================================================
            Thank you for your business!            
==================================================

============================================================
FULL RECEIPT (Single Item)
============================================================

==================================================
                  TECH STORE                   
--------------------------------------------------
Date:                         August 14, 2026
Time:                          02:30 PM
--------------------------------------------------
ITEM                             QTY        PRICE
--------------------------------------------------
Laptop                            2   $1,299.99
--------------------------------------------------
                             Subtotal: $2,599.98
                            Tax (8%):   $208.00
==================================================
                              TOTAL: $2,807.98
==================================================
            Thank you for your business!            
==================================================

============================================================
KEY TAKEAWAYS
============================================================
  • `{var:>10}` - Right align in 10 spaces
  • `{var:^10}` - Center in 10 spaces
  • `{var:<10}` - Left align in 10 spaces
  • `{var:,.2f}` - Thousands separator with 2 decimals
  • Use `$` prefix for currency formatting
  • `datetime` module for date/time display
  • Tax = subtotal × tax_rate
  • Total = subtotal + tax
============================================================

Explanation:

Receipt Formatting Elements:

Alignment: Use <, >, ^ for left, right, and center alignment.
Width: Specify the field width after the alignment character.
Currency Formatting: {value:,.2f} adds commas and 2 decimal places.
Tax Calculation: tax = subtotal * 0.08 (8%).
Total: total = subtotal + tax.

Formatting Codes Used:

Code	Example	Output
`{var:>10}`	`{total:>10.2f}`	Right-aligns in 10 spaces
`{var:<20}`	`{item:<20}`	Left-aligns in 20 spaces
`{var:^30}`	`{store:^30}`	Centers in 30 spaces
`{var:,.2f}`	`{subtotal:,.2f}`	`2,599.98`
`{var:>9,.2f}`	`{total:>9,.2f}`	`$2,807.98` with right alignment

Key Concepts:

Currency Formatting: Always use :,.2f for money values.
Tax Calculation: Apply tax rate to subtotal.
Alignment: Use alignment to create clean tables.
Date/Time: Use datetime module for professional receipts.
Multi-Item: Store items in a list for flexible processing.

Simplified Version (Directly Matching the Exercise):

# Exact receipt from the exercise
item_name = input("Item name: ")
quantity = int(input("Quantity: "))
price = float(input("Price: $"))

subtotal = quantity * price
tax = subtotal * 0.08
total = subtotal + tax

print("\n" + "=" * 40)
print("ITEM                 QTY       PRICE")
print("-" * 40)
print(f"{item_name:<20} {quantity:>5}  ${price:>8,.2f}")
print("-" * 40)
print(f"{'Subtotal:':>30} ${subtotal:>8,.2f}")
print(f"{'Tax (8%):':>30} ${tax:>8,.2f}")
print(f"{'Total:':>30} ${total:>8,.2f}")
print("=" * 40)

5. Homework Questions (Deep Thinking)

**Qu Question 1 (Code Analysis – Find the Bug):
The following code is supposed to print a report, but the output is incorrect. Identify the bugs and fix them.

name = "John"
salary = 50000
bonus = 0.15
total = salary * (1 + bonus)
print("Employee: " + name)
print("Salary: $" + salary)
print("Bonus: " + bonus * 100 + "%")
print("Total: $" + total)

Sample Answer

Bugs: - `+` concatenation with non‑strings causes `TypeError`. - `bonus * 100` yields a float; cannot concatenate with string. Fix by using f‑strings: ```python print(f"Employee: {name}") print(f"Salary: ${salary:,.2f}") print(f"Bonus: {bonus*100:.1f}%") print(f"Total: ${total:,.2f}") ```

Question 2 (Formatting Challenge):
Take a float input and print it as currency, scientific notation, and percentage.

Sample Answer

```python value = 1234567.891 print(f"Currency: ${value:,.2f}") print(f"Scientific: {value:.3e}") print(f"Percentage: {value*100:.2f}%") ```

Question 3 (Real-World Application – Time Display):

Write a program that:

Asks the user for a number of seconds (integer).
Converts it to hours, minutes, and seconds.
Prints the result in a readable format using f‑strings:
- For 3665 seconds: 1 hour, 1 minute, 5 seconds
- For 125 seconds: 2 minutes, 5 seconds
- For 45 seconds: 45 seconds
Use proper pluralization ("hour" vs "hours").

Sample Answer

"""
TIME DISPLAY
Converts seconds to hours, minutes, and seconds with proper pluralization
"""

print("=" * 60)
print("⏱️  TIME CONVERTER")
print("=" * 60)

# --- Get user input ---
try:
    total_seconds = int(input("\nEnter number of seconds: "))
    if total_seconds < 0:
        print("⚠️ Seconds cannot be negative. Using absolute value.")
        total_seconds = abs(total_seconds)
except ValueError:
    print("❌ Invalid input! Using 0 seconds.")
    total_seconds = 0

print(f"\nConverting {total_seconds} seconds...")
print("-" * 40)

# --- Method 1: Basic conversion ---
print("\nMethod 1: Basic Conversion")
print("-" * 30)

# Calculate hours, minutes, seconds
hours = total_seconds // 3600
remaining = total_seconds % 3600
minutes = remaining // 60
seconds = remaining % 60

print(f"Hours: {hours}")
print(f"Minutes: {minutes}")
print(f"Seconds: {seconds}")

# --- Method 2: With pluralization ---
print("\nMethod 2: With Pluralization")
print("-" * 30)

# Helper function for pluralization
def pluralize(value, singular, plural=None):
    """Returns the appropriate singular or plural form."""
    if plural is None:
        plural = singular + "s"
    return singular if value == 1 else plural

# Build the time string with proper pluralization
time_parts = []

if hours > 0:
    time_parts.append(f"{hours} {pluralize(hours, 'hour')}")
if minutes > 0:
    time_parts.append(f"{minutes} {pluralize(minutes, 'minute')}")
if seconds > 0 or not time_parts:  # Show seconds if no hours/minutes
    time_parts.append(f"{seconds} {pluralize(seconds, 'second')}")

result = ", ".join(time_parts)
print(f"Result: {result}")

# --- Method 3: Complete function with formatting ---
print("\nMethod 3: Complete Time Display Function")
print("-" * 30)

def format_time(seconds):
    """
    Converts seconds to a human-readable time string.
    Examples:
        3665 → "1 hour, 1 minute, 5 seconds"
        125 → "2 minutes, 5 seconds"
        45 → "45 seconds"
        0 → "0 seconds"
    """
    if seconds == 0:
        return "0 seconds"
    
    hours = seconds // 3600
    remaining = seconds % 3600
    minutes = remaining // 60
    secs = remaining % 60
    
    parts = []
    if hours > 0:
        parts.append(f"{hours} {'hour' if hours == 1 else 'hours'}")
    if minutes > 0:
        parts.append(f"{minutes} {'minute' if minutes == 1 else 'minutes'}")
    if secs > 0:
        parts.append(f"{secs} {'second' if secs == 1 else 'seconds'}")
    
    return ", ".join(parts)

# Test with the examples
test_values = [3665, 125, 45, 7200, 3600, 61, 1, 0]
print("\nTest Cases:")
print("-" * 30)

for value in test_values:
    formatted = format_time(value)
    print(f"{value:>6} seconds → {formatted}")

# --- Method 4: Advanced - With zero padding for display ---
print("\nMethod 4: Time Format (HH:MM:SS)")
print("-" * 30)

def format_time_hhmmss(seconds):
    """
    Formats time as HH:MM:SS with zero padding.
    Example: 3665 → "01:01:05"
    """
    hours = seconds // 3600
    remaining = seconds % 3600
    minutes = remaining // 60
    secs = remaining % 60
    
    return f"{hours:02d}:{minutes:02d}:{secs:02d}"

print(f"3665 seconds → {format_time_hhmmss(3665)}")
print(f"125 seconds  → {format_time_hhmmss(125)}")
print(f"45 seconds   → {format_time_hhmmss(45)}")

# --- Interactive demo ---
print("\n" + "-" * 40)
print("INTERACTIVE DEMO")
print("-" * 40)

while True:
    user_input = input("\nEnter seconds (or 'quit' to exit): ").strip()
    
    if user_input.lower() == 'quit':
        print("Goodbye!")
        break
    
    try:
        seconds = int(user_input)
        if seconds < 0:
            print("⚠️ Please enter a positive number.")
            continue
        
        formatted = format_time(seconds)
        hhmmss = format_time_hhmmss(seconds)
        print(f"  {seconds} seconds = {formatted}")
        print(f"  Time format: {hhmmss}")
        
    except ValueError:
        print("❌ Please enter a valid integer.")

print("\n" + "=" * 60)
print("KEY TAKEAWAYS")
print("=" * 60)
print("  • Use `//` for floor division (hours, minutes)")
print("  • Use `%` for remainder (remaining seconds)")
print("  • Create a helper function for pluralization")
print("  • Build time parts in a list and join with commas")
print("  • Use `format_time_hhmmss` for clock-style display")
print("  • Handle edge cases: 0, 1, negative values")
print("=" * 60)

Sample Output:

============================================================
⏱️  TIME CONVERTER
============================================================

Enter number of seconds: 3665

Converting 3665 seconds...
----------------------------------------

Method 1: Basic Conversion
------------------------------
Hours: 1
Minutes: 1
Seconds: 5

Method 2: With Pluralization
------------------------------
Result: 1 hour, 1 minute, 5 seconds

Method 3: Complete Time Display Function
------------------------------

Test Cases:
------------------------------
  3665 seconds → 1 hour, 1 minute, 5 seconds
   125 seconds → 2 minutes, 5 seconds
    45 seconds → 45 seconds
  7200 seconds → 2 hours
  3600 seconds → 1 hour
    61 seconds → 1 minute, 1 second
     1 seconds → 1 second
     0 seconds → 0 seconds

Method 4: Time Format (HH:MM:SS)
------------------------------
3665 seconds → 01:01:05
125 seconds  → 00:02:05
45 seconds   → 00:00:45

----------------------------------------
INTERACTIVE DEMO
----------------------------------------

Enter seconds (or 'quit' to exit): 3665
  3665 seconds = 1 hour, 1 minute, 5 seconds
  Time format: 01:01:05

Enter seconds (or 'quit' to exit): 125
  125 seconds = 2 minutes, 5 seconds
  Time format: 00:02:05

Enter seconds (or 'quit' to exit): quit
Goodbye!

============================================================
KEY TAKEAWAYS
============================================================
  • Use `//` for floor division (hours, minutes)
  • Use `%` for remainder (remaining seconds)
  • Create a helper function for pluralization
  • Build time parts in a list and join with commas
  • Use `format_time_hhmmss` for clock-style display
  • Handle edge cases: 0, 1, negative values
============================================================

Explanation:

Time Conversion Logic:

Hours: hours = total_seconds // 3600 (floor division)
Remaining Seconds: remaining = total_seconds % 3600 (modulo)
Minutes: minutes = remaining // 60
Seconds: seconds = remaining % 60

Pluralization:

def pluralize(value, singular, plural=None):
    if plural is None:
        plural = singular + "s"
    return singular if value == 1 else plural

Building the Time String:

Create a list of parts (e.g., ["1 hour", "1 minute", "5 seconds"])
Join with commas: ", ".join(parts)
Only include parts that are greater than 0.

Edge Cases Handled:

0 seconds → "0 seconds"
1 hour, 1 minute, 1 second → correct singular forms
2 hours, 0 minutes → only shows "2 hours" (skips zeros)
Negative numbers → convert to positive or handle

Question 4 (ASCII Art with print()):

Write a program that prints the following shapes using only print() statements. Use escape sequences, sep, and end where appropriate.

Shape 1:

  *
 ***
*****

Shape 2 (Diamond):

   *
  ***
 *****
*******
 *****
  ***
   *

Bonus: Make the size of the diamond configurable by the user.

Sample Answer

"""
ASCII ART
Demonstrates print() with escape sequences and formatting
"""

print("=" * 60)
print("🎨 ASCII ART GENERATOR")
print("=" * 60)

# --- Shape 1: Triangle ---
print("\n" + "-" * 40)
print("SHAPE 1: TRIANGLE")
print("-" * 40)

print("\nMethod 1: Using print() statements directly")
print("  *")
print(" ***")
print("*****")

print("\nMethod 2: Using loops")
triangle_size = 3
for i in range(1, triangle_size + 1):
    stars = "*" * (2 * i - 1)
    spaces = " " * (triangle_size - i)
    print(spaces + stars)

print("\nMethod 3: Using end parameter")
for i in range(1, triangle_size + 1):
    stars = "*" * (2 * i - 1)
    spaces = " " * (triangle_size - i)
    # Print spaces without newline, then stars with newline
    print(spaces, end="")
    print(stars)

# --- Shape 2: Diamond ---
print("\n" + "-" * 40)
print("SHAPE 2: DIAMOND")
print("-" * 40)

print("\nMethod 1: Direct print statements")
print("   *")
print("  ***")
print(" *****")
print("*******")
print(" *****")
print("  ***")
print("   *")

print("\nMethod 2: Using loops")
diamond_size = 4  # Number of rows in the top half

# Top half (including middle)
for i in range(1, diamond_size + 1):
    stars = "*" * (2 * i - 1)
    spaces = " " * (diamond_size - i)
    print(spaces + stars)

# Bottom half
for i in range(diamond_size - 1, 0, -1):
    stars = "*" * (2 * i - 1)
    spaces = " " * (diamond_size - i)
    print(spaces + stars)

print("\nMethod 3: Using join and list comprehension")
rows = []
for i in range(1, diamond_size + 1):
    rows.append(" " * (diamond_size - i) + "*" * (2 * i - 1))
for i in range(diamond_size - 1, 0, -1):
    rows.append(" " * (diamond_size - i) + "*" * (2 * i - 1))
print("\n".join(rows))

# --- Bonus: Configurable Diamond ---
print("\n" + "-" * 40)
print("BONUS: CONFIGURABLE DIAMOND")
print("-" * 40)

def draw_diamond(size):
    """
    Draws a diamond of the specified size.
    Size = number of rows in the top half.
    """
    if size < 1:
        print("Size must be at least 1.")
        return
    
    print(f"\nDiamond of size {size}:")
    print("-" * 30)
    
    # Top half (including middle)
    for i in range(1, size + 1):
        spaces = " " * (size - i)
        stars = "*" * (2 * i - 1)
        print(spaces + stars)
    
    # Bottom half
    for i in range(size - 1, 0, -1):
        spaces = " " * (size - i)
        stars = "*" * (2 * i - 1)
        print(spaces + stars)

# Test with different sizes
draw_diamond(3)
draw_diamond(4)
draw_diamond(5)

# --- Interactive version ---
print("\n" + "-" * 40)
print("INTERACTIVE VERSION")
print("-" * 40)

while True:
    try:
        user_input = input("\nEnter diamond size (2-10, or 'quit' to exit): ").strip()
        
        if user_input.lower() == 'quit':
            print("Goodbye!")
            break
        
        size = int(user_input)
        if 2 <= size <= 10:
            draw_diamond(size)
        else:
            print("Please enter a size between 2 and 10.")
            
    except ValueError:
        print("Please enter a valid integer.")

print("\n" + "=" * 60)
print("ADDITIONAL ASCII ART SHAPES")
print("=" * 60)

def draw_square(size):
    """Draws a square of the given size."""
    print(f"\nSquare ({size}x{size}):")
    for i in range(size):
        if i == 0 or i == size - 1:
            print("*" * size)
        else:
            print("*" + " " * (size - 2) + "*")

def draw_rectangle(width, height):
    """Draws a rectangle of the given dimensions."""
    print(f"\nRectangle ({width}x{height}):")
    for i in range(height):
        if i == 0 or i == height - 1:
            print("*" * width)
        else:
            print("*" + " " * (width - 2) + "*")

def draw_pyramid(height):
    """Draws a pyramid of the given height."""
    print(f"\nPyramid (height {height}):")
    for i in range(1, height + 1):
        spaces = " " * (height - i)
        stars = "*" * (2 * i - 1)
        print(spaces + stars)

def draw_hollow_diamond(size):
    """Draws a hollow diamond of the given size."""
    print(f"\nHollow Diamond (size {size}):")
    
    # Top half (including middle)
    for i in range(1, size + 1):
        spaces = " " * (size - i)
        if i == 1:
            stars = "*"
        else:
            stars = "*" + " " * (2 * i - 3) + "*"
        print(spaces + stars)
    
    # Bottom half
    for i in range(size - 1, 0, -1):
        spaces = " " * (size - i)
        if i == 1:
            stars = "*"
        else:
            stars = "*" + " " * (2 * i - 3) + "*"
        print(spaces + stars)

# Demonstrate additional shapes
draw_square(5)
draw_rectangle(8, 4)
draw_pyramid(5)
draw_hollow_diamond(5)

print("\n" + "=" * 60)
print("KEY TAKEAWAYS")
print("=" * 60)
print("  • Use `print()` with string multiplication: `'*' * 5`")
print("  • Use `end=''` to prevent newlines")
print("  • Use `sep=''` to remove spaces between arguments")
print("  • Escape sequences: `\\n` for newline, `\\t` for tab")
print("  • Loops + string multiplication create repeated patterns")
print("  • `print('\\n'.join(rows))` prints multiple lines at once")
print("=" * 60)

Sample Output:

============================================================
🎨 ASCII ART GENERATOR
============================================================

----------------------------------------
SHAPE 1: TRIANGLE
----------------------------------------

Method 1: Using print() statements directly
  *
 ***
*****

Method 2: Using loops
  *
 ***
*****

Method 3: Using end parameter
  *
 ***
*****

----------------------------------------
SHAPE 2: DIAMOND
----------------------------------------

Method 1: Direct print statements
   *
  ***
 *****
*******
 *****
  ***
   *

Method 2: Using loops
   *
  ***
 *****
*******
 *****
  ***
   *

Method 3: Using join and list comprehension
   *
  ***
 *****
*******
 *****
  ***
   *

----------------------------------------
BONUS: CONFIGURABLE DIAMOND
----------------------------------------

Diamond of size 3:
------------------------------
  *
 ***
*****
 ***
  *

Diamond of size 4:
------------------------------
   *
  ***
 *****
*******
 *****
  ***
   *

Diamond of size 5:
------------------------------
    *
   ***
  *****
 *******
*********
 *******
  *****
   ***
    *

----------------------------------------
INTERACTIVE VERSION
----------------------------------------

Enter diamond size (2-10, or 'quit' to exit): 3

Diamond of size 3:
------------------------------
  *
 ***
*****
 ***
  *

Enter diamond size (2-10, or 'quit' to exit): quit
Goodbye!

============================================================
ADDITIONAL ASCII ART SHAPES
============================================================

Square (5x5):
*****
*   *
*   *
*   *
*****

Rectangle (8x4):
********
*      *
*      *
********

Pyramid (height 5):
    *
   ***
  *****
 *******
*********

Hollow Diamond (size 5):
    *
   * *
  *   *
 *     *
*       *
 *     *
  *   *
   * *
    *

============================================================
KEY TAKEAWAYS
============================================================
  • Use `print()` with string multiplication: `'*' * 5`
  • Use `end=''` to prevent newlines
  • Use `sep=''` to remove spaces between arguments
  • Escape sequences: `\n` for newline, `\t` for tab
  • Loops + string multiplication create repeated patterns
  • `print('\n'.join(rows))` prints multiple lines at once
============================================================

Explanation:

Pattern Logic:

Triangle (size n):

Row i (1-indexed): spaces = n - i, stars = 2*i - 1
Example (n=3): Row 1: 2 spaces, 1 star → " *"

Diamond (size n):

Top half: Same as triangle of size n
Bottom half: Reverse of rows 1 to n-1
Example (n=4): Top 4 rows, bottom 3 rows

String Multiplication:

"*" * 5 → "*****"
" " * 3 → " "

Key Patterns:

range(1, n+1) for ascending rows
range(n-1, 0, -1) for descending rows
print(spaces + stars) combines both

Hollow Diamond Pattern:

First row: only "*"
Middle rows: "" + spaces + ""
Last row: only "*"

Question 5 (Advanced – Custom CSV Exporter):

Write a program that:

Creates a list of dictionaries, each representing a student: {"name": "Alice", "math": 85, "science": 92, "english": 78}.

Uses print() to generate a CSV‑formatted output:

Name,Math,Science,English
Alice,85,92,78
Bob,90,88,95
Charlie,76,82,89

Use sep="," and loops to print each row.
Bonus: Write the output to a file using the file parameter.

Sample Answer

"""
CUSTOM CSV EXPORTER
Demonstrates CSV generation using print() with sep parameter
"""

import csv

print("=" * 60)
print("📊 CUSTOM CSV EXPORTER")
print("=" * 60)

# --- Step 1: Create student data ---
students = [
    {"name": "Alice", "math": 85, "science": 92, "english": 78},
    {"name": "Bob", "math": 90, "science": 88, "english": 95},
    {"name": "Charlie", "math": 76, "science": 82, "english": 89},
    {"name": "Diana", "math": 94, "science": 87, "english": 91},
    {"name": "Eve", "math": 88, "science": 79, "english": 84}
]

print("\nStudent Data:")
for student in students:
    print(f"  {student}")

print("\n" + "-" * 40)
print("METHOD 1: Basic CSV Export (Console)")
print("-" * 40)

# --- Step 2: Export as CSV to console ---
def export_csv_console(data, fields=None):
    """
    Exports data as CSV to the console using print() with sep=','.
    """
    if not data:
        return
    
    # Determine fields (headers)
    if fields is None:
        fields = list(data[0].keys())
    
    # Print header
    print(*fields, sep=",")
    
    # Print each row
    for row in data:
        # Get values in the same order as fields
        values = [str(row.get(field, "")) for field in fields]
        print(*values, sep=",")

print("\nCSV Output:")
export_csv_console(students)

print("\n" + "-" * 40)
print("METHOD 2: CSV Export with Different Formats")
print("-" * 40)

# Export with custom ordering
custom_fields = ["name", "english", "math", "science"]
print("\nCustom field order:")
export_csv_console(students, custom_fields)

# --- Step 3: Bonus - Export to file ---
print("\n" + "-" * 40)
print("BONUS: EXPORT TO FILE")
print("-" * 40)

def export_csv_file(data, filename="students.csv", fields=None):
    """
    Exports data as CSV to a file using print() with file parameter.
    """
    if not data:
        return
    
    if fields is None:
        fields = list(data[0].keys())
    
    # Open file for writing
    with open(filename, 'w', encoding='utf-8') as file:
        # Print header to file
        print(*fields, sep=",", file=file)
        
        # Print each row to file
        for row in data:
            values = [str(row.get(field, "")) for field in fields]
            print(*values, sep=",", file=file)
    
    print(f"✅ Data exported to '{filename}'")

# Export to file
export_csv_file(students, "students.csv")

# --- Step 4: Advanced - Using csv module ---
print("\n" + "-" * 40)
print("METHOD 3: Using csv Module (Standard Library)")
print("-" * 40)

def export_csv_module(data, filename="students_module.csv", fields=None):
    """
    Exports data as CSV using the csv module.
    """
    if not data:
        return
    
    if fields is None:
        fields = list(data[0].keys())
    
    with open(filename, 'w', newline='', encoding='utf-8') as file:
        writer = csv.DictWriter(file, fieldnames=fields)
        writer.writeheader()
        writer.writerows(data)
    
    print(f"✅ Data exported to '{filename}' using csv module")

export_csv_module(students, "students_module.csv")

# --- Step 5: Display the exported file content ---
print("\n" + "-" * 40)
print("VERIFICATION: File Content")
print("-" * 40)

try:
    with open("students.csv", 'r', encoding='utf-8') as file:
        content = file.read()
        print("\nContent of students.csv:")
        print("-" * 30)
        print(content)
except FileNotFoundError:
    print("File not found.")

# --- Step 6: Advanced features ---
print("\n" + "-" * 40)
print("METHOD 4: Advanced CSV Features")
print("-" * 40)

def export_csv_advanced(data, filename="advanced.csv", fields=None, delimiter=","):
    """
    Advanced CSV export with customizable delimiter.
    """
    if not data:
        return
    
    if fields is None:
        fields = list(data[0].keys())
    
    with open(filename, 'w', encoding='utf-8') as file:
        # Print header
        print(*fields, sep=delimiter, file=file)
        
        # Print rows with data type handling
        for row in data:
            values = []
            for field in fields:
                value = row.get(field, "")
                # Handle different data types
                if isinstance(value, str):
                    # Quote strings that contain the delimiter
                    if delimiter in value or '"' in value:
                        value = f'"{value}"'
                values.append(str(value))
            print(*values, sep=delimiter, file=file)
    
    print(f"✅ Advanced data exported to '{filename}'")

export_csv_advanced(students, "advanced.csv", delimiter=";")

# --- Step 7: Auto-detected fields ---
print("\n" + "-" * 40)
print("METHOD 5: Auto-detected Fields")
print("-" * 40)

def auto_detect_fields(data):
    """Automatically detect all unique field names."""
    fields = set()
    for row in data:
        fields.update(row.keys())
    return sorted(list(fields))

# Create data with different fields
mixed_data = [
    {"name": "Alice", "math": 85, "science": 92},
    {"name": "Bob", "math": 90, "english": 95},
    {"name": "Charlie", "science": 82, "english": 89, "history": 78}
]

print("\nMixed data with different fields:")
for row in mixed_data:
    print(f"  {row}")

print("\nAuto-detected fields:", auto_detect_fields(mixed_data))
print("\nCSV Output with auto-detected fields:")
export_csv_console(mixed_data, auto_detect_fields(mixed_data))

# --- Step 8: CSV with summary statistics ---
print("\n" + "-" * 40)
print("METHOD 6: CSV with Summary Statistics")
print("-" * 40)

def export_csv_with_stats(data, filename="students_stats.csv"):
    """Exports CSV with summary statistics appended."""
    if not data:
        return
    
    fields = list(data[0].keys())
    fields_without_name = [f for f in fields if f != "name"]
    
    with open(filename, 'w', encoding='utf-8') as file:
        # Header
        print(*fields, sep=",", file=file)
        
        # Data rows
        for row in data:
            values = [str(row.get(field, "")) for field in fields]
            print(*values, sep=",", file=file)
        
        # Summary statistics
        print("\n--- Summary Statistics ---", file=file)
        print("Field,Average,Min,Max", file=file)
        
        for field in fields_without_name:
            values = [row[field] for row in data if field in row]
            if values:
                avg = sum(values) / len(values)
                min_val = min(values)
                max_val = max(values)
                print(f"{field},{avg:.2f},{min_val},{max_val}", file=file)

export_csv_with_stats(students, "students_stats.csv")
print("✅ CSV with statistics exported to 'students_stats.csv'")

print("\n" + "=" * 60)
print("KEY TAKEAWAYS")
print("=" * 60)
print("  • Use `print(*list, sep=',')` to print CSV rows")
print("  • Use `file` parameter to write to a file")
print("  • Use `csv` module for more robust CSV handling")
print("  • Fields are the dictionary keys")
print("  • Values are extracted in field order")
print("  • Strings containing commas should be quoted")
print("  • `with open(...) as file:` ensures proper file closing")
print("  • `csv.DictWriter` is the professional approach")
print("=" * 60)

Sample Output:

============================================================
📊 CUSTOM CSV EXPORTER
============================================================

Student Data:
  {'name': 'Alice', 'math': 85, 'science': 92, 'english': 78}
  {'name': 'Bob', 'math': 90, 'science': 88, 'english': 95}
  {'name': 'Charlie', 'math': 76, 'science': 82, 'english': 89}
  {'name': 'Diana', 'math': 94, 'science': 87, 'english': 91}
  {'name': 'Eve', 'math': 88, 'science': 79, 'english': 84}

----------------------------------------
METHOD 1: Basic CSV Export (Console)
----------------------------------------

CSV Output:
Name,Math,Science,English
Alice,85,92,78
Bob,90,88,95
Charlie,76,82,89
Diana,94,87,91
Eve,88,79,84

----------------------------------------
METHOD 2: CSV Export with Different Formats
----------------------------------------

Custom field order:
name,english,math,science
Alice,78,85,92
Bob,95,90,88
Charlie,89,76,82
Diana,91,94,87
Eve,84,88,79

----------------------------------------
BONUS: EXPORT TO FILE
----------------------------------------
✅ Data exported to 'students.csv'

----------------------------------------
METHOD 3: Using csv Module (Standard Library)
----------------------------------------
✅ Data exported to 'students_module.csv' using csv module

----------------------------------------
VERIFICATION: File Content
----------------------------------------

Content of students.csv:
------------------------------
Name,Math,Science,English
Alice,85,92,78
Bob,90,88,95
Charlie,76,82,89
Diana,94,87,91
Eve,88,79,84

----------------------------------------
METHOD 4: Advanced CSV Features
----------------------------------------
✅ Advanced data exported to 'advanced.csv'

----------------------------------------
METHOD 5: Auto-detected Fields
----------------------------------------

Mixed data with different fields:
  {'name': 'Alice', 'math': 85, 'science': 92}
  {'name': 'Bob', 'math': 90, 'english': 95}
  {'name': 'Charlie', 'science': 82, 'english': 89, 'history': 78}

Auto-detected fields: ['english', 'history', 'math', 'name', 'science']

CSV Output with auto-detected fields:
english,history,math,name,science
,,85,Alice,92
95,,90,Bob,
89,78,,Charlie,82

----------------------------------------
METHOD 6: CSV with Summary Statistics
----------------------------------------
✅ CSV with statistics exported to 'students_stats.csv'

============================================================
KEY TAKEAWAYS
============================================================
  • Use `print(*list, sep=',')` to print CSV rows
  • Use `file` parameter to write to a file
  • Use `csv` module for more robust CSV handling
  • Fields are the dictionary keys
  • Values are extracted in field order
  • Strings containing commas should be quoted
  • `with open(...) as file:` ensures proper file closing
  • `csv.DictWriter` is the professional approach
============================================================

Explanation:

CSV Export Methods:

Method 1: Using print() with sep=","

# Header
print(*fields, sep=",")
# Row
print(*values, sep=",")

Method 2: Using print() with file parameter

with open(filename, 'w') as file:
    print(*fields, sep=",", file=file)
    for row in data:
        print(*values, sep=",", file=file)

Method 3: Using csv module (Professional)

import csv
with open(filename, 'w', newline='') as file:
    writer = csv.DictWriter(file, fieldnames=fields)
    writer.writeheader()
    writer.writerows(data)

Key Concepts:

Fields (Headers): The dictionary keys become the CSV headers.
Value Extraction: Values are extracted in the same order as fields.
String Conversion: All values are converted to strings.
Quoting: Values containing commas or quotes should be quoted.
File Handling: Use with statement for proper file closure.
Delimiter: Default is comma, but can be changed (e.g., semicolon).

CSV Module vs Manual:

Feature	Manual `print()`	`csv` Module
Simplicity	Simple for basic needs	More complex but robust
Quoting	Manual handling	Automatic
Delimiters	Manual	Configurable
Edge Cases	Prone to errors	Handles correctly
Professional	Less professional	Standard approach

Why Quote Strings?

# Without quotes: "Alice" → Alice (okay)
# With comma: "Smith, John" → Smith, John (problem!)
# Quoted: "Smith, John" → "Smith, John" (correct)

6. Summary Checklist (For Student Self-Review)

I can print single and multiple values using print().
I understand how sep controls the separator between arguments.
I understand how end controls the ending character.
I can use sep and end together to create formatted output.
I can use f‑strings to embed variables and expressions in strings.
I can format numbers with decimal places, thousands separators, and percentages.
I can align text using f‑string formatting specifiers (>, <, ^).
I know common escape sequences (\n, \t, \\, \").
I can create tables and progress bars using print() parameters.
I understand the difference between f‑strings, .format(), and % formatting.
I know that print() can write to files using the file parameter (advanced).

7. Additional Challenge: The Report Generator

Learning Objective

Write a program that generates a full sales report from user input.

Instructions:

Ask the user for:
- Company name
- Report date
- Number of products (N)
For each product (1 to N), ask for:
- Product name
- Quantity sold
- Unit price
Calculate for each product:
- Subtotal (quantity × price)
- Tax (8% of subtotal)
- Total (subtotal + tax)
Calculate overall totals (all products combined).
Print a professional report with:
- Company name and date at the top
- A table of all products with proper alignment, currency formatting, and thousands separators
- Summary totals at the bottom
- A footer with "Report generated on [current date]"

Sample Output:

=============================================================
                     ACME CORPORATION
                 SALES REPORT - 2026-08-11
=============================================================

Product                 Qty    Unit Price     Subtotal      Tax     Total
-----------------------------------------------------------------------
Laptop                   2      $1,299.99    $2,599.98   $208.00 $2,807.98
Monitor                  3        $349.50    $1,048.50    $83.88 $1,132.38
Keyboard                 5         $59.99      $299.95    $24.00   $323.95
-----------------------------------------------------------------------
                                 TOTAL:      $3,948.43   $315.88 $4,264.31
=============================================================
Report generated on 2026-08-11 14:30:25

Hint: Use loops, lists to store product data, and f‑strings with alignment for the table.

Previous | Tutorial index | Next

Tutorial 8: Outputting Data (print())

Learning Objective

1. Introduction

2. Code Examples (Annotated)

3. Quiz (Check Your Understanding)

4. Exercises (In-Class / Lab Practice)

5. Homework Questions (Deep Thinking)

6. Summary Checklist (For Student Self-Review)

7. Additional Challenge: The Report Generator

Learning Objective

Tutorial 8: Outputting Data (`print()`)