String manipulation questions

[goldtech]

Hi,

Replacing strings in a text (likely an XML) file. Some newbie
questions...

....
while line:
counter=counter +1
if line.find(newst ring) != -1:
print 'match at line'+str(count er)
newline = line.replace(ol dstring, newstring)
fileOUT.write(n ewline)
line=fileIN.rea dline()
.....

Question1: The replace method - If a string does not have the target
replacement "newstring" , then newline equals oldstring? Ie. oldstring
is not changed in any way? Seems to be what I observe but just want to
confirm this.

Question2: I'm using "line.find(news tring) != -1..." because I want
to print when a replacement happens. Does "line.replace.. ." report
indirectly somehow when it replaces?
Thanks

P.S. I know I should be using XSLT to transform XML - but the above
seems to work for small text changes.

[Duncan Booth]

Re: String manipulation questions

goldtech <goldtech@world post.comwrote:

Question1: The replace method - If a string does not have the target
replacement "newstring" , then newline equals oldstring? Ie. oldstring
is not changed in any way? Seems to be what I observe but just want to
confirm this.

Yes.

>
Question2: I'm using "line.find(news tring) != -1..." because I want
to print when a replacement happens. Does "line.replace.. ." report
indirectly somehow when it replaces?

Just do the line.replace() and then test for a change.

Question 3 (which I'm sure you meant to ask really) ...
No, you shouldn't be using a while loop here. Use a for loop and the
enumerate builtin:

for counter, line in enumerate(fileI N):
newline = line.replace(ol dstring, newstring)
if newline != line:
print 'match at line', counter+1
fileOUT.write(n ewline)

[goldtech]

Re: String manipulation questions

snip...

>
for counter, line in enumerate(fileI N):
newline = line.replace(ol dstring, newstring)
if newline != line:
print 'match at line', counter+1
fileOUT.write(n ewline)

"enumerate" - haven't seen that before. Nice!

Thanks