John W. Krahn schreef:
You can do both in a single loop like this:
tie my @bestand, 'Tie::File', $best or die "Kon het bestand niet binden: ", $!;
for ( reverse 0 .. $#bestand ) { $bestand[ $_ ] =~ s{\[\d+/\d+/\d+\s\d+:\d+\]\s}{}; splice @bestand, $_, 1 if $bestand[ $_ ] !~ /^<.*>/; }
Note that you have to start at the end of the array for splice() to remove the correct element.
Can you explain this a bit further? I read about splice in the perlop page, but don't quite see through it yet.
Suppose that you have an array:
# index 0 1 2 3 4 5 6 7 my @array = qw/ a b c d e f g h /;
And you loop through it starting with the first element:
for ( 0 .. $#array ) {And you want to remove the element 'c':
splice @array, $_, 1 if $array[ $_ ] eq 'c';
The for(each) loop creates a list (0,1,2,3,4,5,6,7) and iterates through that list setting $_ to the value of each element of that list. When $_ == 2 and $array[2] eq 'c' then splice() will remove that element from @array and now $array[2] eq 'd' and $array[3] eq 'e', etc. In other words, all the elements after 'c' move "down" and the array is shortened by one element. In the next iteration of the loop $_ becomes 3 and the contents of $array[2] (which used to be $array[3]) are missed by the test in the loop. Perhaps this example may help:
$ perl -le'
my @array = ( q/c/ ) x 8;
for ( 0 .. $#array ) {
splice @array, $_, 1 if $array[ $_ ] eq q/c/;
}
print @array . " @array";
'
4 c c c cHowever, if you reverse the list:
$ perl -le'
my @array = ( q/c/ ) x 8;
for ( reverse 0 .. $#array ) {
splice @array, $_, 1 if $array[ $_ ] eq q/c/;
}
print @array . " @array";
'
0You can see that every element was seen and removed by splice().
Another method is to use the in-place edit variable along with the @ARGV array
although this method does not really edit the file "in-place".
{ local ( $^I, @ARGV ) = ( '', <*.log> );
while ( <> ) { s{\[\d+/\d+/\d+\s\d+:\d+\]\s}{}; next unless /^<.*>/; print; } }
What does $^I do? "The current value of the inplace-edit extension. Use undef to disable inplace editing. (Mnemonic: value of -i switch.)" isn't really helpful, I'm afraid.
No it isn't. That is because it is described in perlrun.pod under the entry for the -i switch.
perldoc perlrun
John -- use Perl; program fulfillment
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