<p>我的函数要求用户输入一个7个字符的数字。但当我定义它时,它不会运行。为什么??感谢您的帮助</p>
<pre><code>def eticketNum():
while True:
eTickNum = input('please enter eticket number:')
if len(eTickNum) == 7:
break
print ('Sorry, entry is invalid. Your e-ticket number has to be 7 characters long.')
eTickNum = eTickNum.lower()
# next part of function (I guess)
</code></pre>