Question

Write a program named "cleanDocument.pl" that will do the following:

• Reads two parameters from the command line (@ARGV)
  • The first parameter is the name of a file and the second parameter is a word
  • If no command line parameters are present, it asks the user to input the values
• Opens the text file that is passed as the first command line argument
• Loops through the lines of the text file and replaces all occurrence of the word (the second command line parameter) with an equal number of dashes (that is the same amount of dashes as the word length)
• It then overwrites the file with the new replaced data

Below is an example of how the program works:

Calling the Perl file on the command line like so:

$ cleanDocument.pl document.txt bobsled

or

$ cleanDocument.pl
$ What file do you want to open? document.txt
$ What word do you want to replace? bobsled

If the file looks like below:

$ cat document.txt

I like to use my bobsled during the winter. Whenever I bobsled I have a lot of fun.

Then it will be become:

$ cat document.txt

I like to use my ------- during the winter. Whenever I ------- I have a lot of fun.

Answer 1

Given question, let us implement following points in question as cleanDocument.pl, Below is Solution perl cleanDocument.pl snippet with detailed explaination using comments,

use warnings;

# take input argument file name and word to replace
my ($fileName, $word) = @ARGV;

if(not defined $fileName)
{
    # request file name to user as specified in question.
    print "What file do you want to open? ";
    $fileName = <STDIN>;
    
    # Remove new line end of input  
    chomp $fileName;
}
if(not defined $word)
{   
    # as specified in question prompt user to enter word name
    print "What word do you want me to replace? ";
    $word =  <STDIN>;
    chomp $word;
}


@newLines = ();
# open file, throw error and exit if no file exist
open(my $fhr, '<', $fileName) or die "file '$fileName' not present $!\n";
while (my $file_data = <$fhr>)
{
    chomp $file_data;

    # for word replacement with equal number of dashes
    $word_replacement = "-" x length($word);
    if($file_data =~ m/$word/)
    {
        # if string matches with specified word,
        # replace word with word_replacement store in file_data variable.
        $file_data =~ s/$word/$word_replacement/g;
    }
    # write newLines with new file data
    push @newLines, $file_data;
}

open(my $fhw, '>', $fileName) or die "Could not open file '$fileName' $!\n";
# for each new lines, wite file with modified lines
for(@newLines)
{
    print $fhw "$_\n";
}

Output:

Test for no command line parameters,