擅长:python、mysql、java
<p>变量<code>z</code>和{<cd2>}是字符串。Python不支持从一个字符串中减去另一个字符串。在</p>
<p>如果要显示数字,则必须将其转换为浮点或整数:</p>
<pre><code>print int(z) - int(f),"years ago",x, " first took an airplane."
</code></pre>
<p>这些字符串首先是因为<code>raw_input</code><a href="http://docs.python.org/library/functions.html#raw_input" rel="nofollow">always returns a string</a>。在</p>