Answer 1

Answer 2

Answer 3

类似的东西：

flag = True
while flag:
    try:
       value = input(message)
    except SyntaxError:
        value = None
    if value is None: 
        print "Blank value. Enter floating point number"

对于带输入的空白​​值，这可以捕获异常并使用print语句提醒用户