燃脂心率与BMI计算器循环异常求助：年龄输入循环无法正常退出

我正在开发一款燃脂心率与BMI计算器，要求可处理错误输入并循环请求正确输入，完成后进入下一项输入。计算公式如下：

• 燃脂心率=(220 - age) * 0.7
• BMI=703 * lbs / height**2（身高单位为英寸）

我为年龄、身高、体重输入分别编写了while循环，但输入有效年龄后，第一个循环仍持续重复执行。以下是我的代码与作业示例输出：

#Calculate ideal fat burning heart rate and BMI
#(220 - age) * .7 for fat burning heart rate
#BMI = 703 * lbs / height**2 (in)

print("Welcome to the Weber State University Performance Lab!")
print("Please utilize the following calculator to find your ideal fat burning heart rate and BMI.")

#Age entry
while True:
    try: 
        age = float(input("Please enter your age: "))
        if age <= 0:
            raise TypeError ("Please enter a number greater than zero.")
        break
    except ValueError:
            print("Invalid input.")
            print("Please enter your age in numeric format.")
    except TypeError as err:
            print(err)
    except:
            print("Invalid input.")
while True:
    #Height entry
    try: 
        height = float(input("Please enter your height in inches: "))
        if height <= 0:
            raise TypeError ("Please enter a number greater than zero.")
        break
    except ValueError:
            print("Invalid input.")
            print("Please enter your height in inches in numeric format.")
    except TypeError as err:
            print(err)
    except:
            print("Invalid input.")

while True:
    #Weight Entry
    try: 
        weight = float(input("Please enter your weight in pounds: "))
        if weight <= 0:
            raise TypeError ("Please enter a number greater than zero.")
        break
    except ValueError:
            print("Invalid input.")
            print("Please enter your weight in pounds in numeric format.")
    except TypeError as err:
            print(err)
    except:
            print("Invalid input.")

print("Your age:", age, "years old.")
print("Your height:", height, "inches tall.")
print("Your weight", weight, "lbs")

print("Your ideal fat burning heart rate is", float(round((220 - age) * .7)), "BPM.")
print("Your Body Mass Index is", float(round((703 * (weight / height**2)))))

作业示例输出：

Welcome to the Weber State University Human Performance Lab!
Please utilize the following calculator to find your ideal fat burning heart rate and BMI.

Enter age: forty
Invalid age. Must be a number.
Re-enter age: 40
Enter height in inches: hi
Invalid inches value. Must be a number.
Re-enter height in inches: 0
Invalid inches value. Must be positive.
Re-enter height in inches: 69.25
Enter weight in pounds: dog
Invalid pounds value. Must be a number.
Re-enter weight in pounds: -3
Invalid pounds value. Must be positive.
Re-enter weight in pounds: -20
Invalid pounds value. Must be positive.
Re-enter weight in pounds: 150.5

Age = 40
Height = 69.25"
Weight = 150.5 pounds

Fat Burning Heart Rate = 126 bpm
Body Mass Index = 22.1

问题排查与修复 #

你的代码逻辑本身无语法错误，但存在几个可能导致误解或不规范的问题：

1. 异常类型误用：你用TypeError处理数值小于等于0的错误，但TypeError是用于处理数据类型不匹配的异常，这类值不符合要求的场景应该用ValueError，虽然不影响功能，但不符合Python异常使用规范。

2. 提示信息混淆：你的输入提示和错误提示与作业示例不一致，比如示例中错误后会显示Re-enter age:，而你的代码一直用Please enter your age:，可能导致你误以为循环未退出。

3. 缩进错误（核心排查点）：如果输入有效年龄后循环仍重复，最可能的原因是第二个while循环被意外嵌套在第一个循环内部（缩进错误）。请检查代码缩进，确保三个while循环是同级独立的。

修复后的代码 #

以下是调整后的代码，修复了异常类型，同步了示例提示信息，确保逻辑正确：

# Calculate ideal fat burning heart rate and BMI
# (220 - age) * .7 for fat burning heart rate
# BMI = 703 * lbs / height**2 (in)

print("Welcome to the Weber State University Human Performance Lab!")
print("Please utilize the following calculator to find your ideal fat burning heart rate and BMI.\n")

# Age entry
while True:
    try:
        age = float(input("Enter age: "))
        if age <= 0:
            raise ValueError("Invalid age. Must be positive.")
        break
    except ValueError as err:
        if "could not convert string to float" in str(err):
            print("Invalid age. Must be a number.")
        else:
            print(err)
        age = input("Re-enter age: ")
        continue

# Height entry
while True:
    try:
        height = float(input("Enter height in inches: "))
        if height <= 0:
            raise ValueError("Invalid inches value. Must be positive.")
        break
    except ValueError as err:
        if "could not convert string to float" in str(err):
            print("Invalid inches value. Must be a number.")
        else:
            print(err)
        height = input("Re-enter height in inches: ")
        continue

# Weight Entry
while True:
    try:
        weight = float(input("Enter weight in pounds: "))
        if weight <= 0:
            raise ValueError("Invalid pounds value. Must be positive.")
        break
    except ValueError as err:
        if "could not convert string to float" in str(err):
            print("Invalid pounds value. Must be a number.")
        else:
            print(err)
        weight = input("Re-enter weight in pounds: ")
        continue

print(f"\nAge = {age}")
print(f"Height = {height}\"")
print(f"Weight = {weight} pounds\n")

fat_burning_hr = round((220 - age) * 0.7, 1)
bmi = round(703 * weight / (height ** 2), 1)

print(f"Fat Burning Heart Rate = {fat_burning_hr} bpm")
print(f"Body Mass Index = {bmi}")

关键修复点 #

• 用ValueError替代TypeError处理数值无效的情况，符合Python异常规范。
• 调整提示信息与作业示例完全一致，避免混淆循环阶段。
• 优化错误判断，区分“非数字输入”和“数值非正”的不同提示。
• 使用f-string格式化输出，让结果更简洁易读。

内容的提问来源于stack exchange，提问作者Stephanie Davi