Python输入验证程序语法疑问及演出售票统计功能实现咨询

Hey there! I get it—sometimes Python books skip over these practical, real-world input validation scenarios. Let’s build a solution for your theater group’s ticket tracking that’s robust and easy to follow.

First, let’s outline what we need to do clearly:

• Ask the user for ticket counts for 4 separate shows
• Make sure each input is a valid number between 0 and 120 (inclusive)
• If someone enters something invalid (like a letter, or a number over 120), show an error and ask again
• Finally, calculate the total tickets sold and the average attendance per show

Here’s a complete, working Python script that does all this:

total_tickets = 0
num_shows = 4

for show in range(1, num_shows + 1):
    while True:
        try:
            # Get input from user and convert to integer
            tickets = int(input(f"Enter number of tickets sold for show {show}: "))
            # Check if the number is within the valid range
            if 0 <= tickets <= 120:
                total_tickets += tickets
                break  # Exit the loop since we have valid input
            else:
                print("Error: Ticket count must be between 0 and 120. Please try again.")
        except ValueError:
            # Handle cases where user enters non-numeric text
            print("Error: Please enter a valid whole number.")

# Calculate average attendance
average_attendance = total_tickets / num_shows

# Display final results
print("\n--- Ticket Sales Summary ---")
print(f"Total tickets sold: {total_tickets}")
print(f"Average attendance per show: {average_attendance:.1f}")

Let’s break down the key parts so you understand every step:

• Outer Loop for Shows: The for show in range(1, 5) loop runs 4 times (once for each show), so we collect input for each performance.
• Inner Validation Loop: The while True loop keeps running until we get a valid input. This is how we force the user to try again if they mess up.
• Handling Non-Numbers: The try-except block catches ValueError—this happens when someone enters something like "abc" instead of a number. We print an error message and let the loop restart.
• Range Check: After confirming the input is a number, we check if it’s between 0 and 120. If not, we show an error and loop back to ask again.
• Calculations: We add each valid ticket count to total_tickets, then divide by 4 to get the average. The :.1f formats the average to one decimal place for readability.

Here’s what it looks like when someone uses the program (including invalid inputs):

Enter number of tickets sold for show 1: 150
Error: Ticket count must be between 0 and 120. Please try again.
Enter number of tickets sold for show 1: hundred
Error: Please enter a valid whole number.
Enter number of tickets sold for show 1: 100
Enter number of tickets sold for show 2: 95
Enter number of tickets sold for show 3: 0
Enter number of tickets sold for show 4: 120

--- Ticket Sales Summary ---
Total tickets sold: 315
Average attendance per show: 78.8

This script is flexible too—if you ever need to track more shows, just change the num_shows variable to the new number!

内容的提问来源于stack exchange，提问作者jercai