擅长:python、mysql、java
<p>您的<code>operator</code>变量保存一个<em>字符串</em>。必须使用该字符串来确定要执行的实际操作。</p>
<p>像这样的:</p>
<pre><code>if operator == "+":
realanswer = rn1 + rn2
elif operator == "-":
realanswer = rn1 - rn2
elif operator == "/":
realanswer = rn1 / rn2
elif operator == "*":
realanswer = rn1 * rn2
else
raise Exception('Bad operator {}'.format(operator))
</code></pre>
<p>或者更好地使用<a href="https://docs.python.org/2/library/operator.html" rel="nofollow">^{<cd1>} module</a>:</p>
<pre><code># top of your program
import operator
my_operators = { '+': operator.add,
'-': operator.sub,
'*': operator.mul,
'/': operator.div }
# ...
# and later:
realanswer = my_operators[operator](rn1,rn2)
</code></pre>
<p>当然,在实际的应用程序中,您可能需要处理“无效”的用户输入。例如,使用正确的异常处理。但这是另一个故事。。。</p>