Shell Programming and Scripting

/*
The HelloWorld class implements an application that
simply prints "Hello World!" to standard output.
//You can add comments
*/
class HelloWorld {
    public static void main(String[] args) {
//Let's print Hello World
        System.out.println("Hello World!");
    } /* some comments */
} //end of class

<comments>
/*
The HelloWorld class implements an application that
simply prints "Hello World!" to standard output.
//You can add comments
*/
/* some comments */
//end of class
</comments>

#!/usr/local/bin/perl

use strict;
use warnings;

my $mlcom=0; # multiline comment
my $line;
my @outarr;

if (@ARGV == 0) { print "Missing argument!\n"; exit 1; }

if (@ARGV >= 2) { print "Too many arguments!\n"; exit 1; }

my $infile="$ARGV[0]";
my $outfile='comments.dat';

open(I,$infile) or die "Error opening input file: $!\n";
my @data=<I>;
close(I);

push @outarr, "<comments>\n";

 foreach my $line (@data) {
 chomp($line);

 if ($mlcom == 1 && $line !~ /\*\//) {
  push @outarr, "$line\n";
  next;
 }
 elsif ($mlcom == 1 && $line =~ /\*\//) {
 push @outarr, "$line\n";
 $mlcom=0;
 next;
 }

 if ($line =~ /\/\*/ && $line =~ /\*\//) {
 $line =~ s!^[^/]+!! ;
 push @outarr, "$line\n";
 next;
 }
 elsif ($line =~ /\/\//) {
 $line =~ s!^[^/]+!! ;
 push @outarr, "$line\n";
 next;
 }
 elsif ($line =~ /^\/\*/ && $line !~ /\*\//) {
 $mlcom=1;
 push @outarr, "$line\n";
 next;
 }
 else {
 next;
 }
}

push @outarr, "</comments>\n";

open(O,">$outfile") or die "Error opening output file: $!\n";
print O @outarr;
close(O)

$ cat myfile.cpp
/*
The HelloWorld class implements an application that
simply prints "Hello World!" to standard output.
//You can add comments
*/
class HelloWorld {
    public static void main(String[] args) {
//Let's print Hello World
        System.out.println("Hello World!");
    } /* some comments */
} //end of class
$ 
$ ./pickcomm.pl
Missing argument!
$ 
$ ./pickcomm.pl myfile.cpp another.cpp
Too many arguments!
$ 
$ ./pickcomm.pl myfile.cpp 
$
$ cat comments.dat
<comments>
/*
The HelloWorld class implements an application that
simply prints "Hello World!" to standard output.
//You can add comments
*/
//Let's print Hello World
/* some comments */
//end of class
</comments>
$

#!/bin/sh

if [ -f  $1 ]; then
echo " file $1 exists"
else
echo "file $1 does not exists"
fi
exit 1

#  but I want to check if file is .java or .c++ not a simple file (-f), I don't know how to do it..
# if all are ok I call awk

BEGIN awk'

regular expression for comments /*...*/, //.

END{print comments}'

#!/bin/sh

if [ -f  $1 ]; then
echo "file $1 exists"
else
echo "file $1 does not exists"
exit 1 #needs to be before the "fi" line, else the script will never run the remaining parts of the script.
fi

ext=$(echo $1 | sed 's/.*\.//')

if [ "$ext" = "c++" ] || [ "$ext" = "java" ]; then
echo "file $1 is a .$ext file"
else
echo "file $1 is neither a .c++ nor a .java file!"
exit 1
fi

file HelloWorld.java exists
file HelloWorld.java is a .java file