擅长:python、mysql、java
<p>loop for是一种简单的方法</p>
<pre><code>def count_code(str):
count = 0
for i in range(len(str)-3):
# -3 is because when i reach the last word, i+1 and i+2
# will be not existing. that give you out of range error.
if str[i:i+2] == 'co' and str[i+3] == 'e':
count +=1
return count
</code></pre>