我想更改要求输入数字以仅允许三位数字的要求。将用户输入限制为3个整数
shootnum = None
while True:
try:
shootnum = int(input("Enter today's shoot number > "))
break
except ValueError:
print("Invalid number, please try again.")
我需要改变以适应ValueError?
我想更改要求输入数字以仅允许三位数字的要求。将用户输入限制为3个整数
shootnum = None
while True:
try:
shootnum = int(input("Enter today's shoot number > "))
break
except ValueError:
print("Invalid number, please try again.")
我需要改变以适应ValueError?
你为什么不只是简单的输入限制为3个位数:
shootnum = int(input("Enter today's shoot number > ")[:3])
print(shootnum)
如果您与0
开头的数字有问题,那么你可以做以下代替:
shootnum = (int(input("Enter today's shoot number > ")))
shootnum = (str(shootnum))
shootnum = int(shootnum[:3])
print((shootnum))
只是说:
if x <= 999 and x >= 100:
print("Yes")
else:
print("No.")
或者更惯用的'if 100 <= x <= 999:' –
1个正则表达式(由马腾法布尔的启发)
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只检查拍摄是否是一个三位数
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.")
结果如下
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.
如果我想允许数字如001一直到999? –
@JonathanPetts所以三位数字可以表示数字,如001? – gaoxinge
只是检查长度
user_input = input()
if len(user_input.strip()) != 3:
raise Exception('3 digits allowed')
你仍然需要检查输入的是一个数字
为什么不提高'ValueError',所以程序只是继续 –
只需检查'如果100 <= shootnum <= 999' –
如果整数不符合您的要求,则引发'ValueError'! –
与正则表达式'^ \ d {3} $'进行比较,如果失败,则引发'ValueError'(正则表达式可能会有所改进) –