python - 如何检查 float

Question

我正在尝试创建一个嵌套循环来检查用户的输入应该是整数还是 float 。在我的计算器中，每个化合物的速率存储在基于文本输入的整数中，但是我想为 else 语句添加功能以检查输入是整数还是小数。如果它是一个整数，我希望文本生成不带 .0 的数字，但如果它是一个 float ，例如 6.5，我想将该变量保留为一个 float 。

rerun = True

while (rerun):
    print ("Welcome to the interest calculator")
    balance = input ("\nPlease enter your account balance: ")
    interest = input ("\nWhat is the interest rate on the account? (decimal): ")
    rate = input ("\nWhat is the rate that interest is applied? "
                  "\n(Monthly, Quarterly, Annually, Biannually): ")
    balance = float(balance)
    interest = float(interest)
#Convert text to rate variable

    if (rate == "Monthly" or rate == "monthly"):
        compounds = 12
    elif (rate == "Quarterly" or rate == "quarterly"):
        compounds = 4
    elif (rate == "Annually" or rate == "annually"):
        compounds = 1
    elif (rate == "Biannually" or rate == "biannually"):
        compounds = 2

这是我认为应该检查的地方

    else:
        compounds = float(rate)
#Display Data
    print ('interest = ',  type(interest))
    print ('balance = ',  type(balance))
    print ('compounds = ', type(compounds))

    if (compounds == 1):
        print ("\nYour account has a balance of $" + str(balance), "dollars with an interest rate \n"
               "of ", str(interest) + "%", " being applied", str(compounds), "time per year")
    else:
        print ("\nYour account has a balance of $" + str(balance), "dollars with an interest rate \n"
               "of ", str(interest) + "%", " being applied", str(compounds), "times per year")

    total = interest * balance * compounds

    if (total < 1):
        print ("Calculated total = $" + "{:.2f}".format(total) + " cents")
    else:
        print ("Calculated total = $" + "{:.2f}".format(total) + " dollars")
    #while loop to rerun program

    answer = input ("\nType (y) to rerun the program: ")
    if (answer == "y" or "Y"):
        rerun = True
        print ("\n")
    else:
        rerun = False

因此，如果用户输入 1 作为费率，这将落入 else 语句中，因为它不是我预定义的词之一，“您的帐户余额......”应该将化合物显示为 int。如果用户输入 1.5 作为利率，这将落在 else 语句中，因为它不是我预定义的词之一，“您的账户余额......”应该将化合物显示为 float 。

任何人都可以就如何处理这个问题向我提供一些意见吗？我试过用余数、减法和加法来写出它来检查化合物是否大于整数，但我似乎无法正确地写出它。

Answer 1

最初使用float，然后检查is_integer是否为整数并进行相应处理:

>>> f = float(input())
3
>>> f
3.0
>>> f.is_integer()
True

或者更好的是，使用 g format specifier :

>>> f = 1.000
>>> f
1.0
>>> print("{:g}".format(f))
1
>>> f = 3.14
>>> print("{:g}".format(f))
3.14

General format. For a given precision p >= 1, this rounds the number to p significant digits and then formats the result in either fixed-point format or in scientific notation, depending on its magnitude.

The precise rules are as follows: suppose that the result formatted with presentation type 'e' and precision p-1 would have exponent exp. Then if -4 <= exp < p, the number is formatted with presentation type 'f' and precision p-1-exp. Otherwise, the number is formatted with presentation type 'e' and precision p-1. In both cases insignificant trailing zeros are removed from the significand, and the decimal point is also removed if there are no remaining digits following it.