On May 7, 2013, at 11:00 AM, Sherman Willden wrote:
> Lines written to a file are not contiguous.
>
> First I will describe what I want the script to perform and then I will
> include the script at the end of this message. I downloaded the Oreilly
> Programming Perl Version 4 examples. There are 30 directories with 2211
> files. I want each chapter to have a consolidated file with all the examples
> for that chapter. I created the
> consolidate_examples.pl
> script which goes into each directory, reads each file, and then writes the
> files lines to the consolidated_perl4_examples/<directory name>. An example
> is consolidated_perl4_examples/ch00_preface with contains six lines.
> ch27_perl_functions is the largest and has 435 files which results in a
> single file with 870 lines. What I expected is as follows. If the first file
> I read from contains six lines then I expected the resulting consolidated
> file to have the first six lines align with read-from file. But they don't.
> The consolidated file's lines are mixed with the first six lines comming from
> file 1 or file 8 or whatever. The lines read in are not contiguous. For
> example in ch12 the first consolidated line comes from file 004 and the
> second consolidated line comes from 055.
I believe your problem is that you are only reading one line from each input
file. These two lines:
my $line = readline(READ);
print WRITE "$line\n";
should be replaced by
my @lines = readline(READ);
print WRITE @lines;
Note that you do not need to add a newline at the end of each output line, as
the original newline character[s] will be read in with the lines from the input
file.
>
> ------------ SCRIPT --------------
>
> #!/usr/bin/perl
>
> use v5.16.3;
> # use v5.14.2;
> use File::Basename;
> use File::Path;
>
> my $base_directory =
> "/home/sherman/perl_documentation/programming_perl_4_examples/programming_perl_examples/program_listings";
> my $basename_directory = basename($base_directory) || die "Unable to
> determine the basename: $!\n";
> my $write_directory =
> "/home/sherman/perl_documentation/programming_perl_4_examples/consolidated_perl4_examples";
You should have something like this:
my $homedir = '/home/sherman/perl_documentation/programming_perl_4_examples';
and use that for generating the other variables:
my $base_directory = "$homedir/program_listings";
my $write_directory = "$homedir/consolidated_perl4_examples";
which is easier to write, easier to read, and less error-prone.
> if ( not -e "$write_directory" ) {
> mkdir("$write_directory") || die "Unable to create $write_directory:
> $!\n";
> }
You do not have to enclose $write_directory in double-quotes. Doing so can
cause problems (although probably not here.)
If you leave off the newline at the end of your die message, Perl will tell you
the line number of the error, which can be very useful sometimes.
>
> chdir($base_directory) || die "Unable to change directory to
> $basename_directory: $!\n";
>
> opendir(PERLDIR, ".") or die "Unable to open $basename_directory: $!\n";
It is generally better to use undefined lexical variables for file handles:
opendir( my $perldir, '.') or die(...);
> my @docdirs = grep { $_ ne '.' and $_ ne '..' } readdir PERLDIR;
> closedir(PERLDIR) || die "Unable to close $basename_directory:$!\n";
> foreach my $directory ( @docdirs ) {
> chdir("$base_directory/$directory") || die "Unable to change directory to
> $directory: $!\n";
> my $write_file = "$write_directory/$directory";
> opendir(EXAMPLES, ".") or die "Unable to open $directory: $!\n";
> my @docfiles = grep {$_ ne '.' and $_ ne '..'} readdir EXAMPLES;
> closedir(EXAMPLES) || die "Unable to close $directory: $!\n";
> foreach my $file ( @docfiles ) {
> my ( $write, $read );
These two variables don't seem to be used anywhere.
> open(WRITE, ">>$write_file") || die "Unable to open $write_file:
> $!\n";
> open(READ, $file) || die "Unable to open $file: $!\n";
> my $line = readline(READ) || die "Unable to read $file: $!\n";
> print WRITE "$line\n";
> close(WRITE) || die "Unable to close $write_file: $!\n";
> close(READ) || die "Unable to close $file: $!\n";
> }
> }
>
> 1;
>
Good luck!
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