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值。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工作。

任何想法？

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

你所需要的是这样的：

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: ") 

一个while循环，所以码继续重复操作，直至有效的答案，并给出了里面的右输入测试。