python - 强制 raw_input

Question

我将如何实现以下内容:

title_selection = raw_input("Please type in the number of your title and press Enter.\n%s" % (raw_input_string))
if not title:
    # repeat raw_input

Answer 1

title_selection = ''
while not title_selection:
  title_selection = raw_input("Please type in the number of your title and press Enter.\n%s" % (raw_input_string))

需要事先定义title_selection为''，即为空(也为False)。not 将使 False 变为 True(否定)。