擅长:python、mysql、java
<p>为什么不使用<a href="https://docs.python.org/3.5/library/stdtypes.html?highlight=count#str.count" rel="nofollow noreferrer">count function</a>?你知道吗</p>
<p>在这种情况下,代码简单如下:</p>
<pre><code>sentence = input("Please enter a sentence:")
character = input("Please enter a single character:")
counter = sentence.count(character)
print(counter)
</code></pre>
<p>如果出于任何原因,需要使用<em>while</em>循环来完成此任务,可以尝试以下代码:</p>
<pre><code>sentence = input("Please enter a sentence:")
character = input("Please enter a single character:")
idx = 0
counter = 0
while (idx < len(sentence)): # loop over the string using idx
if character == sentence[idx]: # compare each character of the string with character variable
counter += 1
idx += 1
print(counter)
</code></pre>