checking string(longer) within a string(shorter) using string slicing and indexing python

Question

As you can see the program will ask the user for two string, it should ask for the longer string first then it needs to check the entire longer string for instances of the shorter string. If i find one, print out the index the match started at. and the program does this until it checked the entire longer string. I am new to python and I got stuck, if there are any suggestions please put it at a novice level so I understand without jumping into any advance techniques. This program should be cap sensitive as well. I am trying to find the shorter stringer and index it as many times as it appears (see projected output), by using slicing, indexing, and using a loop.

def main():
    longer = [input("First (longer) string: ")]
    shorter = input("Second (shorter) string: ")
    for shorter in longer:
        print("at index ","found a slice of ", shorter)

main

my projected output should be something like this:

longer: she sells seashells by the seashore.
shorter: sea

at index 10 found a slice of sea
at index 27 found a slice of sea

@vishes_shell, But i wish to not use tring.find() and string.rfind() methods. — Alfred H., Oct 12 '16 at 12:05
There is solution that dont use your methods, it uses `re` module. — vishes_shell, Oct 12 '16 at 12:07
I meant without using RE module or importing re. I would would strictly use slicing, indexing, and a loop if possible — Alfred H., Oct 12 '16 at 12:08
Why is that? If that builtin feature, why not make use of it? And what have you tried? — vishes_shell, Oct 12 '16 at 12:09
Its for learning purposes, for example, I learned about how mod works by doing mod without a mod operator. — Alfred H., Oct 12 '16 at 12:13

Karim Tabet · Answer 1 · 2016-10-12T12:52:11.727

0

Well, to get the first occurrence of the shorter string in the longer, you could use:

longer.find(shorter)

As requested in the comment below, you can write your own find method:

def find_str(s, char):
    index = 0

    if char in s:
        c = char[0]
        for ch in s:
            if ch == c:
                if s[index:index+len(char)] == char:
                    return index

            index += 1

    return -1

print(find_str("she sells seashells by the seashore", "sea"))

edited Oct 12 '16 at 12:52

answered Oct 12 '16 at 12:47

Karim Tabet

1,789
1
14
35

is there any way around using the .find? – Alfred H. Oct 12 '16 at 12:50
I've edited my response with a function that does this. – Karim Tabet Oct 12 '16 at 12:52

score 0 · Answer 2 · answered Oct 12 '16 at 13:08

0

Please try this :

a = 'she sells seashells by the seashore'
b = 'sea'
for v in [ i.start() for i in re.finditer(r'' + b + '',a) ]:
    print "at index {0} found a slice {1}".format(v,b)

answered Oct 12 '16 at 13:08

Transhuman

3,527
1
9
15

checking string(longer) within a string(shorter) using string slicing and indexing python

2 Answers2