Question

这是我的一个学校项目代码（我正在Python 2.7.13中编写）：

def euconverter(mon, rate):
    return (mon * rate)

cur = raw_input('Please give me the currency')
mon = raw_input('Please give me the value')
rate = raw_input('Please give me the rate')
while cur == 'EUR' or cur == 'Eur' or cur == 'GBP' or cur == 'Gbp':
    if cur == 'Eur' or cur == 'Eur':
            print (euconverter(mon, rate))
    elif cur == 'GBP' or cur == 'Gbp':
            print (euconverter(mon, rate))
    else:
        if cur != 'EUR' or cur != 'Eur' or cur != 'GBP' or cur != 'Gbp':
            print 'Wrong input'
            break

我收到此错误：

Traceback (most recent call last):
  File "C:/Users/Maple/PycharmProjects/untitled/Mid term Project.py", line 15, in <module>
    print (euconverter(mon, rate))
  File "C:/Users/Maple/PycharmProjects/untitled/Mid term Project.py", line 2, in euconverter
    return int(mon * rate)
TypeError: can't multiply sequence by non-int of type 'str'

此外，如果我在询问货币类型时输入数字值，则程序将退出而不显示任何消息。这是一个学校项目，因此我希望从用户那里得到错误的输入，并需要向他们提供所需的错误消息，同时试图使他们返回并输入正确的消息。

Answer 1

如评论中所述，mon和raw隐式为strings。要转换它们，请使用mon = int(mon)或mon = float(mon)。

请小心，因为您应该注意输入无效（尝试-TypeError块除外）。

一些提示： -最后，如果应该使用and而不是or -这两行之间没有区别：

if cur == 'Eur' or cur == 'Eur':
    print (euconverter(mon, rate))
elif cur == 'GBP' or cur == 'Gbp':
    print (euconverter(mon, rate))

如果有意的话，您可以将它们分组在一起

Answer 2

似乎您要尝试的是提示用户输入并验证输入，然后再次询问输入是否无效。您可以通过将每个raw_input()包裹在带有标志的while循环中来进行尝试。

要验证货币，将输入转换为大写然后再次检查允许的可能性列表将更容易。

要验证金额和费率，可以将它们强制转换为try-except块内的float。

valid_currencies = ['EUR', 'GBP']
cur = None
mon = None
rate = None

is_valid = False
while not is_valid:
    cur = raw_input('Please give me the currency').upper()
    if cur in valid_currencies:
        is_valid = True
    else:
        print 'Not a valid currency'

is_valid = False
while not is_valid:
    try:
        mon = float(raw_input('Please give me the value'))
        is_valid = True
    except ValueError:
        print 'Not a valid value'

is_valid = False
while not is_valid:
    try:
        rate = float(raw_input('Please give me the rate'))
        is_valid = True
    except ValueError:
        print 'Not a valid rate'

print 'Converted amount'
print mon * rate

Answer 3

一些用于文本输入的重构代码如下：

legal_input = ["gbp", "eur", "yen"]
currency = raw_input("Please enter the currency type")
if currency.lower() in legal_input:
    #some code to do the required operations
else:
    print('not a recognised currency type!')

Answer 4

def euconverter(mon, rate):
    return mon * rate


cur = raw_input('Please give me the currency type ')
mon = float(raw_input('Please give me the ammount of money '))
rate = float(raw_input('Please give me the rate of the exchange '))
while True:
    #i dont know how to make the false statement ending the program as well not necessary i think
    if cur == 'EUR' or cur == 'Eur' or cur == 'GBP' or cur == 'Gbp':
        if cur == 'EUR' or cur == 'Eur':
            print (euconverter(mon, rate))
            break
        elif cur == 'GBP' or cur == 'Gbp':
            print (euconverter(mon, rate))
            break
            # I dont know if multiple breaks should be included here
    else:
        print 'wrong input'
        cur = raw_input('Please give me the currency type again correcntly this time ')
        continue

有了大家的提示和帮助，我终于开始运行它，提示用户在错误的货币输入行中输入其他货币，感谢您的帮助，您很快就会再次收到我的来信。

Python-TypeError：无法将序列乘以'str'类型的非整数

4 个答案: