#! /usr/bin/perl
use warnings;
use strict;
use diagnostics;

print "Enter filename to open (text only):\n\n";
my $infile = <STDIN>;
chomp $infile;

unless( -f $infile ) {
    die "Error: file '$infile' is not existing\n";
}
open( my $INFILE, '<', $infile )
    or die "Error: can't open '$infile' for reading: $!\n";

print "Enter filename to SAVE text file as:\n\n";
my $outfile = <STDIN>;
chomp $outfile;

open( my $OUTFILE, '>', $outfile )
    or die "Error: can't open '$outfile' for reading: $!\n";

print qq~Enter string to replace "and" with\n\n~;
my $word = <STDIN>; chomp $word;

print "\n" x 3;

my $count = 0;

while( <$INFILE> ) {
    $count += s/
                \band\b
               /$word/gix;
    print $OUTFILE $_;
} # while

close $INFILE
    or die "Error: can't close '$infile' for reading: $!\n";
close $OUTFILE
    or die "Error: can't close '$outfile' for writing: $!\n";

print qq~There were $count instances of "and" in '$infile'\n";