extract substring by regex from a text file

[Peter Otten]

Alessio wrote:

> I used readlines() to read my text file, then with a for cicle I
> extract line by line the substrings I need by regular expressions

Just in case you didn't know:

    for line in instream:
        ...

looks better, uses less memory, and may be a tad faster than

    for line in instream.readlines():
        ...

Peter