擅长:python、mysql、java
<p>当找不到子字符串时,<a href="http://docs.python.org/2/library/stdtypes.html#str.find" rel="noreferrer">^{<cd1>}</a>返回<code>-1</code>。</p>
<pre><code>>>> line = 'hi, this is ABC oh my god!!'
>>> line.find('?')
-1
</code></pre>
<p>当<a href="http://docs.python.org/2/library/stdtypes.html#str.index" rel="noreferrer">^{<cd3>}</a>提高<code>ValueError</code>时:</p>
<pre><code>>>> line.index('?')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: substring not found
</code></pre>
<p>如果找到子字符串,这两个函数的行为相同。</p>