擅长:python、mysql、java
<p>您的函数没有<code>return</code>值,因此,函数返回<code>None</code>,您可以在函数中使用<code>return</code>而不是<code>print</code>,如下所示:</p>
<pre><code>class GreetingMessage:
def welcome_message(self):
return ("you are welcome to python")
def thank_you_message(self):
return ("Ok Bye Thank You")
def on_process_message(self):
return ("process is on progress")
msg1 = GreetingMessage()
print(msg1.welcome_message())
print(msg1.on_process_message())
print(msg1.thank_you_message())
</code></pre>
<p>输出:</p>
<pre><code>you are welcome to python
process is on progress
Ok Bye Thank You
</code></pre>
<p>请参见此示例,此问题发生在您的程序中:</p>
<pre><code>>>> def fun_tst():
... print('hi')
>>> print(fun_tst())
hi
None
>>> def fun_tst():
... return ('hi')
>>> print(fun_tst())
hi
</code></pre>