How do I make a loop continue down a string?

Question

st = "abXabXAbX"
ch = "A"
st = st.lower()
ch = ch.lower()


for i in st:
    if (i==ch):
       print st.find(i)

I am trying to position of the character "ch" in uppercase and lower case in the string "st". The for loop gets stuck at detecting the first "a", how do I get the loop to move on check the rest of the string?

The loop is not “stuck”, you are just using the `find` function in a weird way. — kirelagin, Oct 28 '14 at 08:05
Have a look at some of the solutions [here](http://stackoverflow.com/questions/4664850/find-all-occurrences-of-a-substring-in-python) — chthonicdaemon, Oct 28 '14 at 09:31
If you've found any of the answers below useful, please accept one of them. — Korem, Oct 31 '14 at 12:07

score 1 · Answer 1 · answered Oct 28 '14 at 07:40

The for loop isn't stuck, but advancing as it should. You think it's stuck because find returns the first occurence of the item it looks for. It always encounters it at index 0, so your code prints 0, 0, 0.

For this to run, you can use enumerate to keep track of the index of the letter:

for i, ltr in enumerate(st):
    if (ltr==ch):
       print i

Adem Öztaş · Answer 2 · 2014-10-28T08:03:38.443

1

>>> st = "abXabXAbX".lower()
>>> ch = "A".lower()
>>> [ ix for ix,item in enumerate(st) if item == ch]
[0, 3, 6]

edited Oct 28 '14 at 08:03

answered Oct 28 '14 at 07:44

Adem Öztaş

20,457
4
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You don't need the `' '.join(st).split()` - you can just do `enumerate(st)`. – chthonicdaemon Oct 28 '14 at 08:01

Andreas Linnemann · Answer 3 · 2014-10-28T15:01:36.960

1

st = "abXabXAbX"
ch = "A"
st = st.lower()
ch = ch.lower()
pos = st.find(ch)
print(pos)

while pos >= 0:
    pos=st.find(ch,pos+1)
    if pos>-1:
        print(pos)

this will give you all positions

edited Oct 28 '14 at 15:01

answered Oct 28 '14 at 07:45

Andreas Linnemann

19
2

more elegant w/o the first print, and then `while pos>=0: print(pos); pos = st.find(ch, pos+1` – Korem Oct 28 '14 at 16:51

How do I make a loop continue down a string?

3 Answers3