当给出一个字母而不是数字时，我如何阻止程序崩溃？

Question

employee = float(raw_input('Employee code number or 0 for guest:') or 0.0)

if employee == isalpha:
    print "Nice try buddy"
    print "Welcome BIG_OLD_BUDDY" 

此代码不能识别字母输入。

Answer 1

有两种方法。

1. 您可以捕获异常并传递。

try:
    employee = float(raw_input('Employee code number or 0 for guest: ') or 0.0)
except KnownException:
    #  You can handle Known exception here.
    pass
except Exception, e:
    # notify user
    print str(e)

1. 检查输入类型，然后执行所需操作。

employee = raw_input('Employee code number or 0 for guest:')

if(employee.isalpha()):
    print "Nice try buddy"
    print "Welcome BIG_OLD_BUDDY"
else:
    print "Your employee no is:" + str(employee)

除非有可能出现未知异常，否则

不会使用try和catch。建议使用if和else来处理事情。

Read more about : why not to use exceptions as regular flow of control

Answer 2

试一试

try:
    employee = float(raw_input('Employee code number or 0 for guest: ') or 0.0)
except ValueError:
    print "Nice try buddy"
    print "Welcome BIG_OLD_BUDDY"

Answer 3

您可以按照另一个答案的建议使用try/except，如果您想使用str.isalpha()，则必须对字符串调用它，而不是将其与字符串进行比较。例如：

employee = raw_input('Employee code number or 0 for guest:')

if employee.isalpha():
    print "Nice try buddy"
    print "Welcome BIG_OLD_BUDDY" 
else:
    employee = float(employee)