Practice: Conditional Logic and Loop Implementation

Now that you understand how to guide your program's execution using conditional statements and loops, it's time to put that knowledge into practice. The following exercises will help solidify your understanding of if, elif, else, while, for, break, and continue. Working through these problems is a significant step towards writing more dynamic and useful Python programs.

Remember, the goal isn't just to get the right answer, but to understand why the code works. Don't hesitate to experiment, modify the examples, and try different approaches.

Exercise 1: Age Group Classifier

Write a Python script that asks the user for their age and then prints a message indicating whether they are a "Minor" (under 18), an "Adult" (18 to 64), or a "Senior" (65 and older).

Guidance:

1. Use the input() function to get the age from the user. Remember that input() returns a string.
2. Convert the input string to an integer using int(). You might want to wrap this in a try-except block later (as learned in Chapter 9) to handle non-numeric input gracefully, but for now, assume valid input.
3. Use an if-elif-else structure to check the age against the defined ranges.
4. Print the corresponding category.

# Get input (Remember to convert to integer)
# age_str = input("Please enter your age: ")
# age = int(age_str)

# Check the age ranges using if/elif/else
# if age < 18:
#     print(...)
# elif age >= 18 and age <= 64: # Or simply: elif age <= 64: since the first 'if' failed
#     print(...)
# else: # Must be 65 or older
#     print(...)

Exercise 2: Countdown with while

Create a script that uses a while loop to count down from 5 to 1, printing each number. After the loop finishes, print "Blast off!".

Guidance:

1. Initialize a variable to store the starting count (e.g., count = 5).
2. Set up a while loop that continues as long as the count is greater than 0.
3. Inside the loop, print the current value of the count.
4. Decrement the count variable by 1 in each iteration (count = count - 1 or count -= 1).
5. After the loop terminates (when the condition count > 0 becomes false), print the final message.

# Initialize counter
# counter = 5

# Loop while counter is positive
# while counter > 0:
    # Print the counter
    # print(counter)
    # Decrement the counter
    # counter -= 1

# Print the final message after the loop
# print("Blast off!")

Exercise 3: Summing Numbers with for

Given the list numbers = [12, 7, 9, 21, 15], write a script using a for loop to calculate and print the sum of all the numbers in the list.

Guidance:

1. Initialize a variable to store the sum, starting at 0 (e.g., total_sum = 0).
2. Use a for loop to iterate through each number in the numbers list.
3. Inside the loop, add the current number to the total_sum.
4. After the loop has processed all the numbers, print the final total_sum.

# Given list
# numbers = [12, 7, 9, 21, 15]

# Initialize sum accumulator
# current_sum = 0

# Iterate through the list
# for num in numbers:
    # Add current number to the sum
    # current_sum += num # Shorthand for current_sum = current_sum + num

# Print the final sum
# print("The sum is:", current_sum)

Exercise 4: Simple Guessing Game with Loop Control

Write a program that simulates a simple number guessing game.

1. Choose a "secret" number (e.g., secret_number = 8).
2. Use a for loop to give the user a limited number of guesses (e.g., 3 attempts). The range() function can be helpful here.
3. Inside the loop, prompt the user for their guess using input() and convert it to an integer.
4. Check if the guess is correct:
   • If correct, print "Correct! You guessed it!" and use break to exit the loop immediately.
   • If incorrect, print "Sorry, that's not it."
5. After the loop finishes (either by guessing correctly or running out of attempts), check if the user guessed correctly. You might need a separate variable (a flag) to track if the correct guess was made. If they ran out of attempts without guessing correctly, print a message like "Sorry, you've run out of attempts. The number was [secret number]."

Guidance:

• You can use range(3) to loop exactly three times.
• A boolean variable like guessed_correctly = False set before the loop and changed to True upon a correct guess can help determine the final message.

# secret_number = 8
# guessed_correctly = False
# max_attempts = 3

# print("Guess the number between 1 and 10. You have 3 attempts.")

# for attempt in range(max_attempts):
    # guess_str = input(f"Attempt {attempt + 1}: Enter your guess: ")
    # guess = int(guess_str)

    # if guess == secret_number:
        # print("Correct! You guessed it!")
        # guessed_correctly = True
        # break # Exit the loop
    # else:
        # print("Sorry, that's not it.")

# After the loop, check if the user succeeded
# if not guessed_correctly:
    # print(f"Sorry, you've run out of attempts. The number was {secret_number}.")

(Optional Enhancement for Exercise 4): Modify the guessing game to use continue. If the user enters a guess outside a valid range (e.g., less than 1 or greater than 10), print an error message and use continue to skip the rest of the current loop iteration and proceed directly to the next attempt without penalizing them for the invalid input (or perhaps still count it as an attempt, depending on your game rules).

Exercise 5: Printing a Pattern (Nested Loops)

Use nested for loops to print the following pattern:

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

Guidance:

1. The outer loop will control the number of rows (5 in this case).
2. The inner loop will control the number of asterisks printed in the current row. Notice that the number of asterisks in row i is i.
3. Use the print() function's end parameter (print("*", end="")) within the inner loop to print asterisks on the same line.
4. After the inner loop finishes for a given row, use a plain print() statement to move the cursor to the next line before the outer loop starts its next iteration.

# number_of_rows = 5

# Outer loop for rows
# for i in range(1, number_of_rows + 1): # range(1, 6) gives 1, 2, 3, 4, 5
    # Inner loop for columns (asterisks in the current row)
    # for j in range(i): # range(i) gives 0 to i-1, so it runs 'i' times
        # print("*", end="")
    # Move to the next line after printing all asterisks for the current row
    # print()

These exercises cover the core concepts of conditional logic and looping. Try variations, combine concepts (e.g., use if statements inside loops, as in the guessing game), and build confidence in controlling how your Python programs execute.