use warnings;

print "Enter Your BLAST result file name:\t";
chomp($blast = <STDIN>);     # BLAST result file name
print "\n";

print "Enter Your Gene list file name:\t";
chomp($database = <STDIN>);  #  file name
print "\n";

open IN,"$blast" or die "Can not open file $blast: $!";

@ids = ();
@seq_start = ();
@seq_end = ();

while(<IN>){

@feilds = split("\t",$_);
push(@ids,$feilds[0]);
push(@seq_start,$feilds[6]);
push(@seq_end,$feilds[7]);
}
close IN;

open OUT,">Result.fasta" or die "Can not open file $database: $!";


for($i=0;$i<=$#ids;$i++){

($sequence)    = &block($ids[$i]);

($idline,$sequence) = split("\n",$sequence);

    if($seq_start[$i] <= 70){
    $pos_Start = 0;
    }
    else{
    $pos_Start = $seq_start[$i]-70;
    }

    $pos_end = $seq_end[$i]+70;
    if($pos_end >= length($sequence)){
    $pos_end = length($sequence);
    }    

$seqlen = $pos_end - $pos_Start;

$Nucleotides = substr($sequence,$pos_Start,$seqlen);

$Nucleotides =~ s/(.{1,60})/$1\n/gs;

print OUT "$idline\n";
print OUT "$Nucleotides\n";    
}
print "\nExtraction Completed...";

sub block{

$id1 =shift;
print "$id1\n";
$start = ();

open IN3,"$database" or die "Can not open file $database: $!";

$blockseq = "";
while(<IN3>){

    if (($_ =~ /^>/)&&($start)){

    last;
    }

    if (($_ !~ /^>/)&&($start)){

    chomp;
    $blockseq .= $_;
    }

    if (/^>$id1/){

    $start = $.;print "$.\n";#-1;
    $blockseq .= $_;
    }
}
close IN3;

return($blockseq);
}<STDIN>;

I got following errors while running the above code

Use of uninitialized value $seq_start[1] in numeric le (<=) at Blast_Extractor1.pl line 35.
Use of uninitialized value $seq_end[1] in addition (+) at Blast_Extractor1.pl line 42.
Use of uninitialized value in numeric ge (>=) at Blast_Extractor1.pl line 43.
Use of uninitialized value $pos_end in subtraction (-) at Blast_Extractor1.pl line 47.
Use of uninitialized value $sequence in substr at Blast_Extractor1.pl line 49.
Use of uninitialized value $idline in concatenation (.) or string at Blast_Extractor1.pl line 53.