Question

我试图检查用户输入的字符串的长度以及它是否＆lt; 5然而无论多长，它仍然通过我的尝试除了声明

print“”“ 请输入公司的股票代码你希望看到它的最后收盘价。“”“

while True:
   symbol = raw_input("Enter Stock Symbol: ")
   try:
      len(symbol) < 5
      break

   except ValueError:
      print 'Greater than 4 characters, Try again'

print 'Great your stock symbol is less than 5'

Answer 1

你不需要尝试/除了：

while True:
   symbol = raw_input("Enter Stock Symbol: ")
   if len(symbol) > 4:       
      print 'Greater than 4 characters, Try again'
   else:
       print 'Great your stock symbol {} is less than 5'.format(symbol)
       break


In [3]: paste
while True:
   symbol = raw_input("Enter Stock Symbol: ")
   if len(symbol) > 4:       
      print 'Greater than 4 characters, Try again'
   else:
       print 'Great your stock symbol {} is less than 5'.format(symbol)
       break

## -- End pasted text --
Enter Stock Symbol: FOOBAR
Greater than 4 characters, Try again
Enter Stock Symbol: YHOO
Great your stock symbol YHOO is less than 5

在您的代码中：

try:
    len(symbol) < 5 # always checks len
    break # always breaks
except ValueError:

如果您希望将输入转换为try/except来捕获ValueError，那么您将使用int，但它不适用于您的情况。

Answer 2

您必须首先在 if 语句的 try 部分中调用（TypeError 或 ValueError 或 ..Error），并在 except 部分决定如何处理此错误.更多信息：here

while True:
    name = input (': ')
    try:
        if (len (name) >= 4):
            raise ValueError()
            break
    except ValueError:
        print ('Account Created')
    else:
        print ('Invalid Input')

检查用户输入的长度

2 个答案: