writing files while reading files

cal has asked for the wisdom of the Perl Monks concerning the following question:

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Re: writing files while reading files by perigeeV (Hermit) on Jul 21, 2002 at 02:03 UTC
`open(READER, "file1") \|\| die "$!"; open(WRITER, "+<file2") \|\| die "$!"; while(<READER>) { chomp; munge($_); mutilate($_); print WRITER "$_\n"; # Note the filehandle argument to print. }` [download]	[reply] [d/l]
Re: writing files while reading files by dpuu (Chaplain) on Jul 21, 2002 at 02:06 UTC
Simply open the files and use them (its best to open the input file first: if there's an error opening it, you don't want to create the output file). `sub convert { scalar reverse shift } # whatever my $infile = "infile.txt"; my $outfile = "outfile.txt"; open IN, "<$infile" or die "can't read $infile: $!"; open OUT, ">$outfile" or die "can't write $outfile: $!"; while (<IN>) { print OUT convert($_); } close OUT; close IN;` [download] If you're doing only simple conversions, then you don't need to put the formating in a subroutine; but it doesn't do any harm. --Dave.	[reply] [d/l]
Re: writing files while reading files by flounder99 (Friar) on Jul 22, 2002 at 02:11 UTC
One other thing should be mentioned is the `-i` command line switch. It specifies that using `<>` operator will edit files in place with an optional extension to rename the input file. See perlrun for the details. -- flounder	[reply] [d/l] [select]