在Python中如何将磅转换成公斤

Question

我正试图找出如何根据输入输出磅或公斤，这是我的代码：

def conversion():
    amount = input("Please specify the amount: ")
    if type(amount) is int:
        print "derp"
    answer = raw_input("Please choose between converting FROM kilograms/pounds: ")
    if answer == "kilograms":
        return amount * 2.2 
    elif answer == "pounds":
        return amount / 1.45
    else:
        print "Please choose between kilograms and pounds."
        restart = raw_input("Try again? ")
        if restart == "yes":
            conversion()
            return 0
        elif restart == "y":
            conversion()
            return 0 
        else:
            print "Okay, bye."
            return
finalresult = conversion()
print "the final result is", finalresult

Answer 1

当您想从Python中的函数返回多个数据项时，可以返回一个包含两个数据项的tuple：

return (amount * 2.2, "pounds")

或者

return (amount / 2.2, "kilograms")

稍微修改您的函数：

def conversion():
    amount = input("Please specify the amount: ")
    if type(amount) is int:
        print "derp"
    answer = raw_input("Please choose between converting FROM kilograms/pounds: ")
    if answer == "kilograms":
        return (amount * 2.2, "pounds")
    elif answer == "pounds":
        return (amount / 2.2, "kilograms")
    else:
        print "Please choose between kilograms and pounds."
        restart = raw_input("Try again? ")
        if restart == "yes":
            conversion()
            return 0
        elif restart == "y":
            conversion()
            return 0 
        else:
            print "Okay, bye."
            return
finalresult = conversion()
print "the final result is: ", finalresult[0], finalresult[1]

请注意，我还修正了您的体重-公斤例行程序：

$ python /tmp/convert.py 
Please specify the amount: 10
derp
Please choose between converting FROM kilograms/pounds: kilograms
the final result is:  22.0 pounds
$ python /tmp/convert.py 
Please specify the amount: 22
derp
Please choose between converting FROM kilograms/pounds: pounds
the final result is:  10.0 kilograms

那些return 0调用仍然会把事情搞砸：）我希望您应该删除它们。进一步的改进是将接口代码与转换例程分离；您的函数应该更像这样：

def from_kilograms(kilos):
    return kilos * 2.2
def from_pounds(pounds):
    return pounds / 2.2
def conversation():
    while true:
        ans = raw_input("kg or lb: ")
        num = raw_input("mass: ")
        if ans == "kg"
           print from_kilograms(int(num)), " pounds"
        elsif ans == "lb"
           print from_pounds(int(num)), " kilograms"
        else
           print "bye!"
           return

这种分离使得在web服务器软件、GUI、ncurses CLI或普通的旧终端CLI中重用功能更加容易。