[Tutor] FW: find() problem

[Roelof Wobben]

> Subject: Re: [Tutor] FW: find() problem
> From: evert.rol at gmail.com
> Date: Tue, 24 Aug 2010 17:03:07 +0200
> CC: tutor at python.org
> To: rwobben at hotmail.com
> 
> > > > def find(strng, ch, start, step=1):
> > > > index = start
> > > The problem lies here, if you do a print on index, it never gets past
> > > the first index of the number, so
> > > your while loop below goes into an infinite loop.
> > > 
> > > For example:
> > > find('starfruit','t',0) <- First time will return 1
> > > find('starfruit','t',1) <- Still returns 1. Infinite loop
> > > 
> > > > while 0 <= index < len(strng):
> > > > if strng[index] == ch:
> > > > return index
> > > > index += step
> > > > return -1
> > > >
> > > > fruit=""
> > > > letter=""
> > > > fruit= raw_input("Enter a sort of fruit: ")
> > > > letter = raw_input("Enter the character which must be counted: ")
> > > > start=0
> > > > aantal=0
> > > > while 0 <=start < len(fruit):
> > > > x=find (fruit,letter, start)
> > > > aantal +=1
> > > > start=x
> > > > print "De letter", letter , "komt", aantal , "maal voor in het woord", fruit
> > > >
> > > 
> > > HTH,
> > > Tino
> > 
> > Hello, 
> > 
> > Your right. index get never past 1 
> > But in my opinion when something is found then x will be the place where the character is be found.
> > After that the counter is increased and start gets the value of x.
> > So start should change.
> > 
> > Now finding out why this is not happening.
> 
> You're including the previous found index; so it will just find the character at that same index again. You need to start the next search one index further down the word.


 

Hello Evert.
 
Stupid mistake.
I change start=x to start=x+1 
But still it's not working properly.
 
I can see that on this example.
 
Fruit : banaan
letter : a
 
That a is being found at 2,4,5 which is correct but the programm don't end.
So there's another error somewhere,
 
Roelof

 

> 
> 
> > 
> > But thanks for the help.
> > 
> > Roelof
> > 
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