擅长:python、mysql、java
<pre><code>>>> import string
>>> print string.printable[10:62]
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ
>>> a
'this is a string with some letters 1010'
>>> letters = 0
>>> for i in a:
... if i in string.printable[10:62]:
... letters += 1
...
>>> print letters
28
</code></pre>