count letter in string without using count()

Question

I am trying to do the function count without using count() it is working and everything okay but when I try to search two letters in one word its returning 0. When I try to search 1 word in a letter its working normal.

def count(str, sub):
    found = 0
    for key in str:
        if key == sub:
            found += 1
    return found

str = input("Enter a string: ") #or we can initialize a string
sub = input("Enter a substring: ") #or we can initialize a substring

count(str, sub)

print ("letter: ", sub)
print ("count: ", count(str, sub))

for key in str: will always go one letter at a time, so you can not use existing logic to search for two characters at a time. — lllrnr101
– lllrnr101, Commented Feb 21, 2021 at 11:21
@tbjorch i mean without doing print('bctestbc'.count('bc')) to return 2 — Raphael Eid
– Raphael Eid, Commented Feb 21, 2021 at 11:23
@lllrnr101 yes now I realised that the for for loop will go one letter, any idea to turn into a word not letter by letter? — Raphael Eid
– Raphael Eid, Commented Feb 21, 2021 at 11:24
@VanshSachdeva yes now I realized, i am trying to find another method without letter by letter — Raphael Eid
– Raphael Eid, Commented Feb 21, 2021 at 11:24

Nerveless_child · Accepted Answer · 2021-02-21 11:28:14Z

3

Following your method I suggest you do something like this:

def count(string, sub):
    found = 0
    size = len(sub)
    for i in range(len(string) + 1 - size):
        if string[i:i+size] == sub:
            found += 1
    return found

That way you can use it for any size of sub.

answered Feb 21, 2021 at 11:28

Nerveless_child

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Comments

Wrench · Accepted Answer · 2021-02-21 12:18:54Z

2

def count(string, sub):
    found = 0

    for c in range(len(string)):
        start = c 
        end = -(len(string)-len(sub)-c) if -(len(string)-len(sub)-c) != 0 else None
        if string[start:end] == sub:
            found += 1
    return found

string = input("Enter a string: ") #or we can initialize a string
sub = input("Enter a substring: ") #or we can initialize a substring

print ("letter: ", sub)
print ("count: ", count(string, sub))

edited Feb 21, 2021 at 12:18

Wrench

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answered Feb 21, 2021 at 11:30

Vansh Sachdeva

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Comments

Kashyap gajera · Accepted Answer · 2021-02-21 11:41:08Z

1

Below should work for all length sub strings.

def count(str, sub):
    found = 0
    for i in range(1,len(str)+1): #iterate for all length substrings
        for j in range(len(str)-i+1): #iterate for different starting positions of substrings.
            key = str[j:j+i]
            if key == sub:
                found += 1
    return found

edited Feb 21, 2021 at 11:41

answered Feb 21, 2021 at 11:25

Kashyap gajera

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1 Comment

Raphael Eid Over a year ago

as you can see here that this method is not working for this letter tested on programiz and uploaded on imgur

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