Question

我正在尝试制作一个程序，如果我输入一个正数，那么它会进一步执行，但是如果我输入一个负数或一个字母，它应该打印“房价必须是一个正数＆＃39;它应该再次要求输入。这是我到目前为止所做的，但当我输入一个数字时，我得到一个AttributeError，当我输入一封信时，我得到一个NameError。

import math

while True:
    home_price = input('Enter the price of your dreams house')
    if home_price.isdigit():
        if home_price > 0:    
            home_price = int(house_price)
            break
        else:
            print('House price must be a positive number only')

Answer 1

如果要保持循环运行直到收到正整数，则可以测试输入的负整数/非数字值，然后继续下一次迭代。否则你可以从循环中断开

while True:
    home_price = input('Enter the price of your dream house: ')

    if not home_price.isdigit() or not int(home_price) > 0:
        print('House price must be a positive integer only')
        continue

    print('The price of your dream house is: %s' % home_price)
    break

Enter the price of your dream house: a
House price must be a positive integer only
Enter the price of your dream house: -1
House price must be a positive integer only
Enter the price of your dream house: 1000
The price of your dream house is: 1000

Answer 2

如果您使用的是Python 2，其input函数对用户输入有eval(..)，而eval("2")则返回int，而不是str

python2 -c 'print(eval("2").__class__)'
<type 'int'>

如果您将input替换为raw_input，那么您的代码将适用于Python 2，而eval不会var response = { "statusCode": 200, "data": { "Response": "R00=00&R01=Balance Added. &R02=59.00&R03=1.00", "TokenStatus": "Used" } }; var retVal = response.data.Response.split('&').reduce(function(acc, ele) { var x = ele.split('='); acc[x[0]] = x[1]; return acc; }, {}); console.log(retVal);。

Answer 3

我建议异常处理。＆＃34; -10＆＃34; .isdigit（）返回false。

import math

while True:
    home_price = input('Enter the price of your dreams house')
    try:
        if int(home_price) > 0:    
            house_price = int(home_price)
            break
        else:
            print('House price must be a positive number only')
    except ValueError:
        continue

Answer 4

这是一种不同的方法：

home_price_gotten = False

while not home_price_gotten:
    try:
        home_price = input('Enter the price of your dream house\n')
        home_price = int(home_price)
        if home_price < 1:
            raise TypeError
        home_price_gotten = True
        break
    except ValueError:
        print("Home price must be a number, but '{}' is not.".format(home_price))
    except TypeError:
        print('Home price must be a positive number')


print("Success! Home price is : '{}'".format(home_price))

基本上，在用户给出有效房价之前，循环将询问他一个，并尝试将他的输入转换为数字。如果失败，可能是因为输入不是数字。如果它小于1，则会引发另一个错误。所以你被覆盖了。

顺便说一下，这只适用于python 3。对于python 2，将input()换成raw_input()

AttributeError：＆＃39; int＆＃39;对象没有属性＆＃39; isdigit＆＃39;和NameError

4 个答案: