String manipulation questions

Duncan Booth duncan.booth at invalid.invalid
Wed Apr 9 09:32:55 EDT 2008

goldtech <goldtech at> wrote:

> 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(newstring) != -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(fileIN):
       newline = line.replace(oldstring, newstring)
       if newline != line:
           print 'match at line', counter+1

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