python - 如何验证变量是否在两个指定数字之间？

Question

如何验证用户输入以限制他们只能输入 -5 到 -21 之间的数值？我目前已经设置了这个 while 循环；

while True: 
 if flatNumber.isdigit():
      flatNumber = int(flatNumber)
      if flatNumber>5 and flatNumber<21: 
           print("Enjoy your stay.") 
           break 
      else:  
           flatNumber = input("Please enter your flat number.")
 else: 
    flatNumber = input("Please enter a numerical flat number.")

但是这仅验证 5 到 21 之间的数值？有人可以发布解决方案并解释如何验证 -5 到 -21 之间的数值吗？

Answer 1

您可以使用负值进行简化的链式比较:

if -21 < flatNumber < -5:

str.isdigit 不适用于负数，在验证输入时您几乎应该始终使用 try/except :

while True:
    try: 
        # try to cast to int
        flatNumber = int(input("Please enter your flat number."))
        # if cast was successful make sure it is in range if not ask again
        if not -21 < flatNumber < -5:
            print("Not in range -5 to -21")
            continue
        break # else all is good break the loop
    except ValueError:
           print("Invalid input")

print(flatNumber)