检查输入是否为正整数

Question

我需要检查用户输入的内容是否为正数。如果不是，我需要以msgbox的形式打印错误。

number = input("Enter a number: ")
   ###################################

   try:
      val = int(number)
   except ValueError:
      print("That's not an int!")

上面的代码似乎没有用。

有什么想法吗？

Answer 1

while True:
    number = input("Enter a number: ")
    try:
        val = int(number)
        if val < 0:  # if not a positive int print message and ask for input again
            print("Sorry, input must be a positive integer, try again")
            continue
        break
    except ValueError:
        print("That's not an int!")     
# else all is good, val is >=  0 and an integer
print(val)

Answer 2

你需要的是这样的：

goodinput = False
while not goodinput:
    try:
        number = int(input('Enter a number: '))
        if number > 0:
            goodinput = True
            print("that's a good number. Well done!")
        else:
            print("that's not a positive number. Try again: ")
    except ValueError:
        print("that's not an integer. Try again: ")

while循环，所以代码会继续重复，直到给出有效的答案，并测试其中的正确输入。