Question

我正在尝试验证用户的输入。我只希望用户能够输入正整数或负整数。所有其他输入（即任何带字母的输入）都应该被拒绝

我现在有下面的代码，但是我收到了错误。我假设它与数据类型有关，但我不确定如何解决这个问题。

import re

number =input("Please enter a number: ")
number=int(number)
while not re.match("^[0-9 \-]+$", number):
    print ("Error! Make sure you only use numbers")
    number = input("Please enter a number: ")
print("You picked number "+ number)

Answer 1

如果您关心的是输入是有效的数字文字，请不要使用正则表达式。 int将正确解析字符串或引发异常。

while True:
    s = input("Please enter a number: ")
    try:
        n = int(s)
        break
    except ValueError:
        print("Error! Make sure you only use numbers")
print("You picked number " + n)

Answer 2

正则表达式需要字符串作为输入，而不是数字。因此，您不必将字符串强制转换为数字，并且可以省略number=int(number)。

这是working demo：

number = "2"
if not re.match("^[0-9 -]+$", number):
    print ("Error! Make sure you only use numbers")
print("You picked number "+ number)

Answer 3

import re

while  True:
    number =input("Please enter a number: ")
       # number=int(number) -- This raise an error, for regexp you need use "str"

    #while not re.match("^[0-9 \-]+$", number):
    # in [0-9 \-]  after 9 you use whitespace
    # Also in [0-9 \-]  if minus at the and, not need use backslash

if  re.match("-?\d+$", number) : # minus may be only in first position
    break

print ("Error! Make sure you only use numbers")
    # deleted     number = input("Please enter a number: ")

print("You picked number "+ number)

Answer 4

answer = input(" ")#asks the user for an answer
ansnum = re.match("[0-9 \-]",answer)#checks to see if answer only contains numbers
while not ansnum: #whilst the answer does not contain numbers do....
   answer = input("Enter numbers as your answer: ")#asks the user for a valid answer
   ansnum = re.match("[0-9 \-]",answer)#checks to see if the answer contains numbers

使用正则表达式验证用户输入是一个整数

4 个答案: