For loop function not returning the correct output

Question

I'm trying to write a program to see how many times a 3-digit substring shows up in a string. For example, the substring "122" would show up in the string "122122" 2 times. However, whenever I run it, it returns 0, even if the substring does actually show up. Can you tell me what's wrong with my function?

def count_substring(string, sub_string):
    count = 0
    for i in range (len(string)): 
        if string[i:i+3] == sub_string:
           count+=1

It doesn't return 0, it returns None. You gotta return count at the end! — Samwise
– Samwise, Commented Mar 21, 2021 at 20:55
You can also just use the built-in count function. Try "122122".count("122")! — Samwise
– Samwise, Commented Mar 21, 2021 at 20:55

Kevin · Accepted Answer · 2021-03-21 20:58:24Z

1

Using @Samwise's comment as a suggestion:

def count_substring(string, sub_string):
    return string.count(sub_string)

Although, since that's a one-liner, if you only need to run this function once, you may not even want to break it off into its own function. So just use string.count(sub_string) where you need it.

answered Mar 21, 2021 at 20:58

Kevin

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berkayln · Accepted Answer · 2021-03-21 20:57:00Z

0

This can help you:

def count_substring(string, sub_string):
    return string.count(sub_string)

answered Mar 21, 2021 at 20:57

berkayln

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