擅长:python、mysql、java
<pre><code>'''
s: main string
sub: sub-string
count: number of sub-strings found
p: use the found sub-string's index in p for finding the next occurrence of next sub-string
'''
count=0
p=0
for letter in s:
p=s.find(sub,p)
if(p!=-1):
count+=1
p+=1
print count
</code></pre>