[Tutor] String.find won't - why?
Mon, 29 Oct 2001 00:13:31 +0100
On 0, Danny Kohn <firstname.lastname@example.org> wrote:
> Hi again.
> Thanks for all the comments on the readline(s) issue. I have understood this fully.
> But please bear with me. Unfortunally the next step in this little program is as problematic for me.
> Am trying to remove all 0D 0A (Hex). Thought this was done through the following while loop.
> The file is attached.
0D 0A? That's CRLF right, a newline on Windows/DOS. Ok.
> The first round things works nicely. The 0D 0A (Hex) is found and removed. Pos is correctly 142.
> The second round things behave more strangely. Pos will get a wrong value (178) but there just is no 0D 0A (Hex) there and so the i:pos string will get to short.
> Running w2k. Why on earth is this behaving wrongly?
> t = open('d:/Experiment.txt', 'r')
> text = t.read() # Read text
> print text
> a = ''
> while i < len(text):
> pos = string.find(text[i:], '\n')
Here, pos gets a position relative to text[i:].
> print pos
> if pos > 0:
> a = a + text[i:pos]
Here you use pos as an index in the whole string.
So you meant a = a + text[i:i+pos].
The reason this works the first time is that it's the same thing with i=0.
> print a
> i = i + pos + 1
Btw, the whole loop can be written
a = string.replace(text, '\n', '')
Hope this helps :)