Re: unreadline function?

one idea is to do the loop like this

my $line = '';
while(1)
{
   $line = $line ? $line : <FH>;
   last unless defined $line;
   unless(isNewRecordLine($line))
   {
      addToRecord($line);
      $line = '';
   }
   else
   {
      processRecord();
   }   
}
[download]

or you could use seek (SEEK_CUR) to get the file position information and store it in some variable and when you detect a new record, you just use seek (SEEK_SET) again to reposition the filepointer.

Have fun!

Comment on Re: unreadline function? Download Code

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Re:x2 unreadline function? by grinder (Bishop) on Mar 01, 2004 at 08:55 UTC
I really hate `unless (cond) { ... } else { ... }` constructs. I think they're better written as `if (not cond) { ... } else { ... }`. It could be I'm an old C programmer, but I find it easier to follow. More importantly, I think your code will fail to process the last record. I would do something like the following: `my @record; while( <FH> ) { chomp; if( /start-delim/ ) { @record and process( @record ); @record = (); } push @record, $_; } @record and process( @record );` [download] If there was an end delimiter, the loop could be flipped around to a do/while, and one could do away with the two calls to process(). I note in passing that davido's idea of setting `$/` is excellent, but it onlys work if the delimiter is a fixed string. If you need an RE to match the delimiter, a different approach is also possible.	[reply] [d/l] [select]

Replies are listed 'Best First'.

Re:x2 unreadline function?
by grinder (Bishop) on Mar 01, 2004 at 08:55 UTC

I really hate unless (cond) { ... } else { ... } constructs. I think they're better written as if (not cond) { ... } else { ... }. It could be I'm an old C programmer, but I find it easier to follow.

More importantly, I think your code will fail to process the last record. I would do something like the following:

my @record;

while( <FH> ) {
    chomp;
    if( /start-delim/ ) {
        @record and process( @record );
        @record = ();
    }
    push @record, $_;
}
@record and process( @record );
[download]

If there was an end delimiter, the loop could be flipped around to a do/while, and one could do away with the two calls to process().

I note in passing that davido's idea of setting $/ is excellent, but it onlys work if the delimiter is a fixed string. If you need an RE to match the delimiter, a different approach is also possible.

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