Hi,
I need to generate a file and before doing so,I have to check the whether the file exists and if so ,is it modified or not .I know in the recent past there have been lot of questions on this but my question is different. I am checking in a different way. i,e I am pushing the contents of the existing file "file1" into any array "@seq1" and the contents of the file to be generated is stored in an array "@seq2". I am using Perl module Algorithm::diff to find the difference of 2 arrays. I want to know is this the right way to find whether the existing file is modified or not ? 
my $flag = 1;
if ( -e $file1 ) { 
print "Script '$file1' already exists\n";
open(FILE1,"$file1");
my @seq1 = <FILE1>;    
close FILE1;
# @seq2 contains the contents of the file to generated.
my $diff = Algorithm::Diff->new( \@seq1, \@seq2 );
my $sep;
my $flag = 1;

$diff->Base( 1 );   # Return line numbers, not indices
while(  $diff->Next()  ) {
next  if $diff->Same();
if(  ! $diff->Items(2) || ! $diff->Items(1) ) {
$flag = 0;
print $diff->Get(qw( Min1 Max1 Max2 )),"\n";
} 
else {
$flag = 0;
$sep = "---\n";
print  $diff->Get(qw( Min1 Max1 Min2 Max2 )),"\n";
}
 print "< $_"   for  $diff->Items(1);
 print $sep;
print "> $_"   for  $diff->Items(2);
}

if($flag == 0) {
print
"User edits,do u want to overwrite the exisiting $file1?";
print "[INFO] Continue ? [no]";
my $answer = <STDIN> ; chomp $answer;
if ($answer =~ /^n/i) {
  print"Not Generated the script '$file1'";
}
....

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In reply to existing file is modified or not by Madam

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