Trina Espinoza wrote:
> I have a file that I want to run multiple actions on. First, the file is
> read in as one long string. I want to
> substitute some words with others so I run a substitution. That seems to
> change the data in the first
> while, HOWEVER, when I run the second while loop on the same data to parse
> my newly reformated file, I get the original file, instead of the newly
> reformated file. . .
>
> Something like the code I'm using:
> -----------------------------
> open(SOURCE, $file);
Make sure to check open's return value
>
> ###Run a substitution that breaks up my string into lines
> while (<SOURCE>) {
> s/something/\nsomething/g;
You are modifying $_, but not writing the contents back to the file. You can
open a temporary file, write the modified contents to it and at the end
rename the temporary file as your original file. The other approach would be
to use $^I (perldoc perlvar, perldoc perlrun, look for the -i flag, $^I is a
mnemonic for the -i command line flag) and the 'null filehandle' (perldoc
perlop)
For e.g.
local $^I = '~';
local @ARGV = ($file);
while (<>) {
s/something/\nsomething/g;
print;
}
The module Tie::File will also interest you, I guess it comes with the
standard distribution of perl 5.8.0 and onwards. You can install it from
http://search.cpan.org if you don't have it.
>
>
> }
> #What I want it to parse a file, which at this point, shoud consist of
> multiple lines.
> #HOWEVER problem is I amI running this command on the same file
>
> while (<SOURCE>) {
> parse SOURCE;
> }
>
> ----------------------------------------------
> Is the best thing to save the outcome of the substitution into a variable
> and read that variable in on the
> second while or is there an easier way? Thanks in advance for the help :)
>
> -T
>
> e.g.
>
> while (<SOURCE>) {
> $newFile = s/something/\nsomething/g;
> }
> #does this even work?
>
> while ($newfile) {
This won't work as $newfile will contain the last modified line of the file
when the while loop on the SOURCE filehandle finishes.
>
> parse stuff ;
> }
>
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