thanks John and Rob for the great enlightenment, they taught me a lot.
I wonder why the following is wrong:
while (($in1=<IN1>) && ($in2=<IN2>))
{
..
}
Ben
Rob Dixon wrote:
> <[EMAIL PROTECTED]> wrote:
> >
> > I need to read from more than one file at a time and do some
> > operation on the strings and join them together, and put into
> > one output file.
> >
> > Here is the code. But I noticed the second file never get
> > read. It must be sth very simple to overcome this. Can anyone
> > give me a hint?
> >
> > thanks,
> > Ben
> >
> > # Usage: perl jointfiles.pl infile1 infile2 outfile
> use strict;
> use warnings;
> > open (IN1, $ARGV[0]);
> > open (IN2, $ARGV[1]);
> > open (OUT, ">$ARGV[2]");
> As John says,
> open IN1, $ARGV[0] or die $!;
> open IN2, $ARGV[1] or die $!;
> open OUT, ">$ARGV[2]" or die $!;
> > print "Input fileis : $ARGV[0], $ARGV[1]n";
> > print "Output file: $ARGV[2]n";
> >
> > while(<IN1>)
> > {
> > chomp;
> > $in1=$_;
> > <IN2>;
> > $in2=$_;
> > printf OUT "$in1$in2n";
> > }
> You need tp think about what happens when the two files are
> different lengths. You may not expect that to happen but your
> code should still handle that case. Some symmetry between the
> handling of the two files would also be nice. Finally you
> should really use 'print' here instead of 'printf'.
> This code reads a line from each file and outputs them both
> until one or other file is exhausted.
> my ($in1, $in2);
> while (defined ($in1 = <IN1>) and defined ($in2 = <IN2>)) {
> chomp ($in1, $in2);
> print OUT "$in1$in2n";
> }
> > close(IN1);
> > close(IN2);
> > close(OUT);
> HTH,
> Rob
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