擅长:python、mysql、java
<p><code>global</code>变量很少是正确答案!您可以使<code>counter</code>成为一个默认为零的参数,并稍微进行重构:</p>
<pre><code>def recAlphaCount(s, counter=0):
if len(s) == 0:
return counter
else:
if s[0].isalpha():
counter += 1
return recAlphaCount(s[1:], counter)
</code></pre>