help with search & replace

[Bill Blue]

I have a text file that has numbers is many places thru out the file
ie "20:22:12" .  I need to be able to create a new file and make
changes only to those numbers above.  I used this to find them

import re,string,sys

if = open("infile.txt","r")
of = open("outfile.txt,"w")
for line in if.xreadlines():
	fs = re.compile(r"\d+:\d+:\d+").findall(line)  # there may be
more than one in a line.
	if fs:
		for num in fs:
			of.write(lne.replace(num,num[0:5]+"00")) # the
replace text is not always the same
	else:
		of.write(line)  # for line where no match is found

The above works if there is only 1 match or number on a line, if there
are more that one then I get multiple lines in the output file.   in
most cases there may be 3-6 matches on one line.

input line is:
another time  01:12:36 the normal time for these is  01:12:45

here is the busted output:

>another time  01:12:00 the normal time for these is  01:12:45  
>another time  01:12:36  the normal time for these is  01:12:00 

I would like to be able to replace all occurences in one line with out
generating multiple output lines.


 Any help on this wold be appreciated.

Bill B.