Python的验证，如果输入是int和大于0

Question

所以我要问客户端重新输入变量如果不是整数，或者是小于或等于0，我不能让它得到一个程序错误，并结束它。

def enter_amount(): 


amount=input("Enter amount:") 
while (not isinstance(amount, int)) or amount<=0: 
    amount=input("The amount can't be negative, please try again:") 
return amount 

试过这个，它总是失败了。如果您有任何想法，我将不胜感激。

Answer 1

您需要输入转换为整数，然后检查该值。由于用户可能会输入垃圾，因此您必须通过捕获值异常来处理整数转换。

def get_amount(): 
    while True: 
     amount = input("Enter amount: ") 
     try: 
      val = int(amount) 
      if val >= 0: 
       break 
      else: 
       print("Amount can't be negative, try again") 
     except ValueError: 
      print("Amount must be a number, try again") 
    return val 

Answer 2

不能使用回的功能之外！把你的代码包装在一个函数中，它应该没问题。

def test(): 
    amount=input("Enter amount:") 
    while (not isinstance(amount, int)) or amount<=0: 
     amount=input("The amount can't be negative, please try again:") 
    print(amount) 
    return amount 

test() 

Answer 3

def getUserAmount(): 
    while True: 
     amount = input("Enter amount: ") 
     try: 
      value = int(amount) 
      if value >= 0: 
       break 
      else: 
       print("Amount is negative, try again") 
     except ValueError: 
      print("Amount must be a number, try again") 

    return value 

main()