Python异常处理- BMI计算器
Python异常处理- BMI计算器
提问于 2022-09-07 01:34:46
我正在编写python中的BMI计算器，并希望添加异常处理。我创建了两个函数。一种是高度转换器，根据用户的输入将高度转换为英尺或米，另一种是重量转换器，根据输入将用户的体重转换为千克或磅。def height_converter(h)和weight_converter(w)函数在用户输入错误时不会重新启动，而下面的代码只要求输入重量和高度。另外，BMI变量返回一个错误，我不知道该做什么。
# BMI CALCULATOR IN PYTHON
import os
from datetime import datetime
# define our clear function
def clear():
# for windows
if os.name == 'nt':
os.system('cls')
# for mac and linux(here, os.name is 'posix')
else:
_ = os.system('clear')
def weight_converter(w):
while True:
try:
global converted
converted = 0
weight_unit = input("What is the weight unit Kgs or Lbs: ")
if weight_unit.upper() == "KG":
converted = w / 1
print("weight in kg is: ", converted)
elif weight_unit.upper() == "LBS":
converted = w / 2.2
print("weight in kg is: ", converted)
else:
raise ValueError(weight_unit)
break
except (ValueError, IOError, IndexError):
print("ERROR")
return converted
def height_converter(h):
while True:
try:
height_unit = input("what is the height unit meters or feet: ")
if height_unit.upper() == "METERS":
converted = h / 1
print("height in meters is: ", converted)
elif height_unit.upper() == "FEET":
converted = h / 3.281
print("height in meters is: ", converted)
break
except(ValueError,IOError,IndexError):
print("ERROR")
return converted
while True:
try:
age = input("How old are you? ")
age = int(age)
weight = input("What is your weight: ")
weight = float(weight)
wconverted = weight_converter(weight)
height = input("What is your height: ")
height = float(height)
hconverted = height_converter(height)
break
except ValueError:
# os.system(clock_settime)
print("No valid integer! Please try again ...")
clear()
BMI = float(wconverted / (hconverted ** 2))
print("Your BMI is: ", BMI, "as of ", date)
print("You are using a", os.name, "system")回答 2
Stack Overflow用户
回答已采纳
发布于 2022-09-07 03:00:46
测试您的代码，在转换函数中，代码块末尾的返回操作实际上没有被执行，因为它在代码块缩进中的逻辑位置。因此，您实际上是向调用这些函数的语句返回一个"None“。
考虑到这一点，下面是您的代码，通过一些调整从权重和高度转换函数返回转换后的值。
# BMI CALCULATOR IN PYTHON
import os
from datetime import date
# define our clear function
def clear():
# for windows
if os.name == 'nt':
os.system('cls')
# for mac and linux(here, os.name is 'posix')
else:
_ = os.system('clear')
def weight_converter(w):
while True:
try:
global converted
converted = 0
weight_unit = input("What is the weight unit Kgs or Lbs: ")
if weight_unit.upper() == "KG":
converted = w / 1
print("weight in kg is: ", converted)
return converted # Made sure a decimal value was being returned
elif weight_unit.upper() == "LBS":
converted = w / 2.2
print("weight in kg is: ", converted)
return converted # Same here
else:
raise ValueError(weight_unit)
except (ValueError, IOError, IndexError):
print("ERROR - Please enter proper unit of measure")
def height_converter(h):
while True:
try:
height_unit = input("what is the height unit meters or feet: ")
if height_unit.upper() == "METERS":
converted = h / 1
print("height in meters is: ", converted)
return converted # And here
elif height_unit.upper() == "FEET":
converted = h / 3.281
print("height in meters is: ", converted)
return converted # And finally here
else:
raise ValueError(height_unit)
except(ValueError,IOError,IndexError):
print("ERROR - Please enter proper unit of measure")
while True:
try:
age = input("How old are you? ")
age = int(age)
weight = input("What is your weight: ")
weight = float(weight)
wconverted = weight_converter(weight)
height = input("What is your height: ")
height = float(height)
hconverted = height_converter(height)
break
except ValueError:
# os.system(clock_settime)
print("No valid integer! Please try again ...")
clear()
BMI = float(wconverted / (hconverted ** 2))
print("Your BMI is: ", BMI, "as of ", date.today()) # You had not defined the variable "date"
print("You are using a", os.name, "system")我使用了一种蛮力方法来确保返回一个值。或者，您可以将函数块中的最后一个返回细化为只有一个返回，但我只是希望在提供快速调整时避免可能出现的范围问题。
这就产生了以下示例结果。
@Una:~/Python_Programs/BMI$ python3 Calculator.py
How old are you? 66
What is your weight: 170
What is the weight unit Kgs or Lbs: lb
ERROR - Please enter proper unit of measure
What is the weight unit Kgs or Lbs: kilos
ERROR - Please enter proper unit of measure
What is the weight unit Kgs or Lbs: lbs
weight in kg is: 77.27272727272727
What is your height: 5.83333
what is the height unit meters or feet: inches
ERROR - Please enter proper unit of measure
what is the height unit meters or feet: feet
height in meters is: 1.7779122218835721
Your BMI is: 24.445876294351564 as of 2022-09-08
You are using a posix system试试看。
Stack Overflow用户
发布于 2022-09-07 02:30:30
在您的weight_converter函数中，只有当用户输入错误输入时，才会返回转换后的值。在Python中，indention确定语句属于哪个代码块。您需要将返回语句放置在与need相同的缩进级别上:这将使它位于while循环之外，并且它基本上会在您中的一个中断之后发生。
height_converter函数也有类似的问题。
另外，您只在其中一个函数中引发ValueError，并且由于在not块中捕获它们，它们不会传播到调用方。
对此代码的异常处理似乎增加了不必要的复杂性。仅仅为了让下一行代码做一些不同的事情而引发一个ValueError是过分的和令人困惑的。下面是weight_converter函数的一个更简单的版本。
def weight_converter(w):
while True:
weight_unit = input("What is the weight unit Kgs or Lbs: ")
if weight_unit.upper() == "KG":
conversion = 1.0
break
elif weight_unit.upper() == "LBS":
conversion = 2.2
break
else
print("ERROR")
converted = w / conversion
print("weight in kg is: ", converted)
return converted未登录的异常会在调用堆栈中传播，直到它们被一个except块捕获为止。如果它们未被捕获，则会导致解释器停止程序，并通常打印堆栈跟踪。如果此代码导致异常，则调用方中的异常处理程序将捕获它们。如果您在此函数中捕获它们，它们将永远无法补偿调用方。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/73629204
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