Determining how many times a substring occurs in a string in Python

Question

I am trying to figure out how many times a string occurs in a string. For example:

nStr = '000123000123' 

Say the string I want to find is 123. Obviously it occurs twice in nStr but I am having trouble implementing this logic into Python. What I have got at the moment:

pattern = '123' count = a = 0 while pattern in nStr[a:]:     a = nStr[a:].find(pattern)+1     count += 1 return count 

The answer it should return is 2. I'm stuck in an infinite loop at the moment.

I was just made aware that count is a much better way to do it but out of curiosity, does anyone see a way to do it similar to what I have already got?

Answer 1

Use str.count:

>>> nStr = '000123000123' >>> nStr.count('123') 2 

A working version of your code:

nStr = '000123000123' pattern = '123' count = 0 flag = True start = 0  while flag:     a = nStr.find(pattern, start)  # find() returns -1 if the word is not found,      #start i the starting index from the search starts(default value is 0)     if a == -1:          #if pattern not found set flag to False         flag = False     else:               # if word is found increase count and set starting index to a+1         count += 1                 start = a + 1 print(count)