擅长:python、mysql、java
<p><code>plaintext</code>是字符串,<code>plaintext[i]</code>也是字符串。<code>15*plaintext[i]</code>乘以字符串,您正试图用<code>+20</code>向字符串添加一个整数。所以只要:</p>
<pre><code>15*int(plaintext[i])+20 #if plaintext is a string of decimals, don't know what exactly you want
</code></pre>
<p>或者我猜你在做一些类似加密的事情,这样你需要用<a href="http://docs.python.org/2/library/functions.html#ord" rel="nofollow"><strong>ord</strong></a>把一个字符转换成整数,然后用它的逆<strong><a href="http://docs.python.org/2/library/functions.html#chr" rel="nofollow">chr</a></strong>:</p>
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