How do your Rewind File Handles? 1

[bryantg]

Hello All,
I am attempting to read two files, I want to compare file1 against file2 then output only the lines that are not found in file1 to out.file

I know how to open the file handles and output to the file handle, but the process only reads the file1 one time.



Is there a way to read each line of FILE1 theN read the complete FILE2 and print each line from FILE2 that is not found in FILE1?

Help and thanks....

 

[MikeLacey]

Bryan,

If file1 is small enough to read into memory you could do something like this.
[tt]
# read all of file1
open(F,"file1&quot||die;
while(<F>){
$file1hash{$_}=1; # into a hash array
}
close(F);

# create the output file
open(OF,&quot;out.file&quot||die;
# then read through file2
open(F,&quot;file2&quot||die;
while(<F>){
print OF $_ unless defined($file1hash{$_});
}
close(F);
[/tt]
Mike
michael.j.lacey@ntlworld.com
Email welcome if you're in a hurry or something -- but post in tek-tips as well please, and I will post my reply here as well.

 

[bryantg]

Mike.................................Thanks A BUNCH!!! It worked like a champ.

but i have a question if i wanted to view what was contained in the hash array how would i print it out???

THANKS AND HAPPY HOLIDAYS!!

 

[MikeLacey]

thanks

This prints a sorted list of keys and the associated values in the file1hash:

foreach $key (sort(keys %file1hash)) {
print $key, '=', $file1hash{$key}, &quot;\n&quot;;
}

That's the usual way you would use this - but you only have a 1 in each value, so you could just say:

foreach $key (sort(keys %file1hash)) {
print &quot;$key\n;
}


Happy holidays,

Mike
michael.j.lacey@ntlworld.com
Email welcome if you're in a hurry or something -- but post in tek-tips as well please, and I will post my reply here as well.