Replace

[Eric]

On 2006-05-06, Tim Williams wrote:
> On 06/05/06, Eric <elw000 at verizonz.net> wrote:
>> I have a string...
>>
>> str = "tyrtrbd =ffgtyuf == =tyryr =u=p ttttff"
>>
>> I want to replace the characters after each '=', what I ended up doing is
>> somthing like this...
>>
>> buf = list(str)
>> newchr = '#'
>>
>> count = 0
>> for i in range(len(buf)):
>>   if buf[count] == '=':
>>     buf[count + 1] = newchr
>>     count = count + 1
>>   else:
>>     count = count + 1
>>
>> newstr = ''.join(buf)
>>
>> Is there a better, faster way of doing it? Using somthing like
>> str.index() dosn't work because...
>>
>
> After you find an '=' you are updating the next chr in the list to '#'
>  then testing the '#' to see if it is an '=' .
>
> This would be quicker as it bypasses testing your self-added '#' , and
> also removes a " count +1"
>
> #Untested
> buf = list(str)
> newchr = '#'
> count = 0
> for i in range(len(buf)):
>   if buf[count] == '=':
>    count = count + 1
>    buf[count] = newchr
> count = count + 1
>
>
> I might have done something like this (using s instead of str)
>
> #untested
>>>> buf = list(s)
>>>> newstr = ''
>>>> while buf:
> ... 	newstr +=  buf.pop(0)  # get the first item in buf and append it to newstr
> ... 	if new[-1]  == '=':
> ... 		newstr += '#'
> ... 		buf.pop(0)  # discard the next item in buf
>
>
> HTH :)

Thanks, I should have included more info about what I was trying to do, just
trying to keep my post short. I was messing around trying to write a simple 
script to decode yenc encoded usenet posts. Yenc uses the '=' before special
chars like '\n', '\r', those chars need to handled differently. Iterating over
each char in a file dosn't sound like the best idea.

import sys
import string

crap = sys.stdin

d42 = string.join([chr((x - 42) % 256) for x in range(256)], '')
d64 = string.join([chr((x - 64) % 256) for x in range(256)], '')

def proccess(crapstring):
  buffer = list(crapstring)

  count = 0
  for count in range(len(buffer)):
    if buffer[count] != '=':
      buffer[count] = buffer[count].translate(d42)
      count = count + 1
    else:
      buffer[count + 1] = buffer[count + 1].translate(d64)
      buffer[count] = ''
      count = count + 1

  newstring = ''.join(buffer)
  return newstring

while 1:
  line = crap.readline()
  if not line:
    break
  if line[:7] != '=ybegin':
    continue
  header = line.split()
  """Do somthing with header sometime"""
  break

linebuf = []
while 1:
  line = crap.readline()
  if line[:5] != '=yend':
    if line[-2:] == "\r\n":
      line = line[:-2]
    pline = proccess(line)
    linebuf.append(pline)
  else:
    break

deccrap = ''.join(linebuf)
sys.stdout.write(deccrap)


This script isn't working for some reason. I'll figure that out someday.