Re^3: reading a line from file two times

if ( $line =~ /NEWTABLE/) {
   seek(FH, (0 - length($line)+tell(FH)), SEEK_CUR);
   $line = <FH>;
   chomp($line);
   print "LINE AFTER SEEK :$line:\n"
}
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Output :-

"LINE AFTER SEEK :EWTABLE:\n"
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why I am missing 'N' after the seek ?

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Re^4: reading a line from file two times by BrowserUk (Patriarch) on Dec 21, 2006 at 04:38 UTC
There's definitely someting screwy with using a negative, relative seek (on Win32). To back up over a line consisting of 8 chars + NL, requires seeking back -6. I'd expect to have to seek back more than the line length, not less to account for the newline? `#! perl -slw use strict; while( <DATA> ) { chomp; print; if( /the line/ ) { my $backup = -length() + 2; print "Backing up $backup places"; seek DATA, $backup, 1; chomp( $_ = <DATA> ); print "?$_?"; } } =output c:\test>junk junk junk more junk the line Backing up -6 places ?the line? other junk yet more junk =cut __DATA__ junk junk more junk the line other junk yet more junk` [download] Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal? "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l]
Re^5: reading a line from file two times by jettero (Monsignor) on Dec 21, 2006 at 05:36 UTC
Should be on systems where `seek($fh, $amount, SEEK_CUR)` works correctly, you'd have to backup over all the characters read. So if the `length($entire_string)` is 10 (including LF or CRLF), that'd be: `seek($fh, -10, SEEK_CUR)`. I do seem to recall that it behaves unexpectedly (for a unix nerd) in windows, but my experience was in foxpro, not perl — that definitely shouldn't count. -Paul	[reply] [d/l] [select]
Re^4: reading a line from file two times by jettero (Monsignor) on Dec 21, 2006 at 03:45 UTC
`seek(FH, (0 - length($line)+tell(FH)), SEEK_CUR);` You are seeking too far back. You're seeking back the length of the string plus the byte-number of your current position... If you wish to use `tell()` to record the old position before your read, then you'd use: `seek(FH, $old_position, SEEK_SET);` instead. -Paul	[reply] [d/l] [select]