如何修复我编写的Python BMI计算器代码？

Got it, let's fix your BMI calculator step by step. Here are the key issues in your code and how to resolve them:

Key Issues in the Original Code #

• Return type mismatch: Your function returns a string (like "Your BMI is 22.5"), but you're trying to compare this string to numeric values (18, 25) later—this will throw a TypeError.
• Incomplete else clause: The final else... is cut off, which causes a syntax error.
• Rigid input type for weight: Using int() for weight means users can't enter decimal values (e.g., 62.5 kg) without an error.
• Minor UX tweak: Adding a space at the end of input prompts makes typing feel more natural.

Fixed Code #

print('BMI calculator V1')
name = input("What's your name? ")
# Use float for weight to support decimal values
weight = float(input("Your weight in Kilograms: "))
height = float(input("Your height in Metres: "))

def calculate_bmi(w, h):
    # Return the numeric BMI value instead of a string
    bmi = w / h ** 2
    return bmi

# Calculate BMI first (numeric value)
user_bmi = calculate_bmi(weight, height)
# Print the formatted BMI string separately
print(f"Your BMI is {user_bmi:.2f}")  # .2f rounds to 2 decimal places for readability

# Now we can compare the numeric BMI value correctly
if user_bmi < 18.5:  # Updated to standard BMI threshold (18.5 instead of 18)
    print(f"{name}, you are underweight")
elif user_bmi > 25:
    print(f"{name}, you are overweight")
else:
    print(f"{name}, you have a healthy weight")

What Changed? #

1. Function returns numeric BMI: The calculate_bmi function now returns the raw number instead of a string, so we can use it for comparisons.
2. Fixed input type: Weight uses float() to accept decimal values.
3. Completed else clause: Added the missing colon and a message for healthy weight.
4. Improved formatting: Used an f-string to print BMI rounded to 2 decimal places (easier to read than a long float).
5. Updated threshold: Changed the underweight cutoff to 18.5, which aligns with standard BMI guidelines (optional, but more accurate).

内容的提问来源于stack exchange，提问作者SepiaAR16