python-3.x - 如何让我的函数区分python中的输入'I'和'II'?
问题描述
我的目标是让用户在 I 和 V 之间输入两个罗马数字并将它们相加。我想以十进制值及其罗马数字等价物显示方程。
但是,当我输入除 I 和 V 之外的值时,该值会被分配为“NoneType”,并且程序会失败。我尝试将返回设置为 str() ,然后稍后调用 int() ,设置 roman num is '': num_value = # 然后在最后返回 num_value ,但都没有奏效。
我认为我遗漏了一些非常基本的东西,它与区分具有重复字符的值有关,例如“I”(没关系)和“II”,它被分配为 NoneType。
firstNumeral = input("please enter a roman numeral between I and V: ")
secondNumeral = input('please enter a second roman numeral between I and V: ')
def get_user_num(roman_num):
if roman_num is 'I':
return int(1)
elif roman_num is 'II':
return int(2)
elif roman_num is 'III':
return int(3)
elif roman_num is 'IV':
return int(4)
elif roman_num is 'V':
return int(5)
elif roman_num is 'VI':
return int(6)
elif roman_num is 'VII':
return int(7)
elif roman_num is 'VIII':
return int(8)
elif roman_num is 'IX':
return int(9)
elif roman_num is 'X':
return int(10)
firstNumber = get_user_num(firstNumeral)
secondNumber = get_user_num(secondNumeral)
totalNumber = firstNumber + secondNumber
def get_roman_number(result_number):
if result_number == 1:
return "I"
elif result_number == 2:
return "II"
elif result_number == 3:
return 'III'
elif result_number == 4:
return 'IV'
elif result_number == 5:
return 'V'
elif result_number == 6:
return 'VI'
elif result_number == 7:
return 'VII'
elif result_number == 8:
return 'VIII'
elif result_number == 9:
return 'IX'
elif result_number == 10:
return 'X'
totalNumeral = get_roman_number(totalNumber)
print('Decimal values {} + {} = {}'.format(firstNumber,secondNumber, totalNumber))
print('Roman Numeral values {} + {} = {}'.format(firstNumeral, secondNumeral, totalNumeral))
当使用除 I 和 V 之外的任何值时,我得到
Traceback (most recent call last):
File ... line 26, in <module>
totalNumber = firstNumber + secondNumber
TypeError: unsupported operand type(s) for +: 'NoneType' and 'NoneType'''
解决方案
firstNumeral = input("please enter a roman numeral between I and V: ")
secondNumeral = input('please enter a second roman numeral between I and V: ')
def get_user_num(roman_num):
if roman_num is 'I':
return int(1)
elif roman_num == 'II':
return int(2)
elif roman_num == 'III':
return int(3)
elif roman_num == 'IV':
return int(4)
elif roman_num == 'V':
return int(5)
elif roman_num is 'VI':
return int(6)
elif roman_num == 'VII':
return int(7)
elif roman_num == 'VIII':
return int(8)
elif roman_num == 'IX':
return int(9)
elif roman_num == 'X':
return int(10)
firstNumber = get_user_num(firstNumeral)
secondNumber = get_user_num(secondNumeral)
print(secondNumber)
totalNumber = firstNumber + secondNumber
def get_roman_number(result_number):
if result_number == 1:
return "I"
elif result_number == 2:
return "II"
elif result_number == 3:
return 'III'
elif result_number == 4:
return 'IV'
elif result_number == 5:
return 'V'
elif result_number == 6:
return 'VI'
elif result_number == 7:
return 'VII'
elif result_number == 8:
return 'VIII'
elif result_number == 9:
return 'IX'
elif result_number == 10:
return 'X'
totalNumeral = get_roman_number(totalNumber)
print('Decimal values {} + {} = {}'.format(firstNumber,secondNumber, totalNumber))
print('Roman Numeral values {} + {} = {}'.format(firstNumeral, secondNumeral, totalNumeral))
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