將用戶輸入限制為3個整數

Question

我想更改輸入數字的要求，以僅允許三位數字。

shootnum = None
while True:
    try:
        shootnum = int(input("Enter today's shoot number > "))
        break
    except ValueError:
        print("Invalid number, please try again.")

我需要更改什么以適應ValueError？

Answer 1

說啊：

if x <= 999 and x >= 100:
    print("Yes")
else:
    print("No.")

Answer 2

1個正則表達式（由MaartenFabré啟發）

import re

while True:
    try:
        shoot = raw_input("Enter today's shoot number > ") # I use python 2.7
        shootnum = int(shoot)
        if not re.match(r'\d{3}$', shoot):
            raise ValueError # can be caught by except
        print shootnum
    except ValueError:
        print("Invalid number, please try again.")

2只需檢查拍攝是否為三位數

while True:
    try:
        shoot = raw_input("Enter today's shoot number > ") # I use python 2.7
        shootnum = int(shoot)
        if len(shoot) != 3 or shoot[0] == '-':
             raise ValueError # can be caught by except
        print shootnum
    except ValueError:
        print("Invalid number, please try again.")

結果如下

Enter today's shoot number > qwer
Invalid number, please try again.
Enter today's shoot number > -12
Invalid number, please try again.
Enter today's shoot number > 123
123
Enter today's shoot number > 1222
Invalid number, please try again.
Enter today's shoot number > 012
12
Enter today's shoot number > 0122
Invalid number, please try again.
Enter today's shoot number > 0
Invalid number, please try again.
Enter today's shoot number > 00
Invalid number, please try again.
Enter today's shoot number > 000
0
Enter today's shoot number > 0000
Invalid number, please try again.

Answer 3

您為什么不簡單地將輸入限制為3位數字：

shootnum = int(input("Enter today's shoot number > ")[:3])
print(shootnum)

如果您對以0開頭的數字有疑問，可以改用以下方法：

shootnum = (int(input("Enter today's shoot number > ")))
shootnum = (str(shootnum))
shootnum = int(shootnum[:3])
print((shootnum))