Question

基本上，我正在建立一个汽车销售计划，其中汽车及其细节被添加到一个类（然后是文本文件，但该部分与我需要的帮助无关）。我正在使用for循环'for x in range（nocars）'来做到这一点。我的输入都在没有验证的情况下工作但现在我需要进行验证，这是我用'carYear'变量完成的，你可以看到while循环。基本上如果年份低于1900，它将继续提示用户重新输入正确的值（每次输入不正确）。到目前为止，这在程序中有效。一旦输入正确的数字，程序应该转到下一个输入下一个变量。然而，它只是再次启动范围过程。我知道这是由'break'引起的，但是我还不知道还有什么方法可以在恢复输入过程时退出while循环。救命？虽然循环被双星号包围，所以你可以找到它。感谢。

 for x in range(nocars):
        print("Car No.", x+1)
        carMake = input("Please enter make: ")
        carModel = input("Please enter model: ")
        carYear = input("Please enter year of manufacture: ")
        **while int(carYear) < 1900 :
            carYear = input("Please enter a valid value: ")
        else:
            break**
        carLitre = input("Please enter the cylinder capacity of the car in litres : ")
        carVal = input("Please enter value in GBP: ")
        carReg = input("Please enter registration number (excluding spaces): ")
        carOwn = input("Please enter the previous ownership (new, second-hand, third-hand, more than three previous owners): ")
        carMile = input("Please enter the mileage: ")
        carMod = input("Please enter any modiciations existing on the car. If there are no modifications, enter 'None': ")                    
        carCond = input("Please enter the condition of the car (VP = Very Poor, P = Poor, A = Average, G = Good, VG = Very Good, P = Pristine: ")
        print("-Customer Details-")
        cusName1 = input("Please enter your forename: ")
        cusName2 = input("Please enter your surname: ")
        cusGen = input("Please enter your gender (Male, Female, Other): ")
        cusAge = input("Please enter your age: ")
        print ("----------")
        print("You have added car(s) to temporary memory. To save this to a text file, select '3' from the following menu and follow the steps...")

        carList.append(CarEntry(carMake, carModel, carYear, carLitre, carVal, carReg, carOwn, carMile, carMod, carCond, cusName1, cusName2, cusGen, cusAge))

Answer 1

你应该在不同的功能中进行验证，如下所示：

carYear = validNumberInput('Please enter the year of manufacture: ', 1900)

将功能分开如下：

def validNumberInput(prompt, minimum):
    while True:
        try:
            value = int(input(prompt))
        except ValueError:
            continue
        if value >= minimum:
            return value

然后根据需要使用不同的提示调用该函数。

您需要为不同类型的验证编写不同的函数，例如空字符串，无效数字，数字范围等。

Answer 2

while-else构造可能没有做你想要的。在else之后的break实际上导致外部for循环中断。尝试摆脱其他部分，看起来像：

while int(carYear) < 1900 :
     carYear = input("Please enter a valid value: ") 
carLitre = input("Please enter the cylinder capacity of the car in litres : ")
carVal = input("Please enter value in GBP: ")
...

如何获得经过验证的输入以进入下一个输入而不是开始新的范围？

2 个答案: