open (OUTPUT, ">$fname.tmp");
        open (DATA, "$fname");

[download]

You should always verify that the file opened correctly before trying to use a possibly invalid filehandle. 

        open OUTPUT, '>', "$fname.tmp" or die "Cannot open '$fname.tmp
+' $!";
        open INPUT,  '<', $fname or die "Cannot open '$fname' $!";

[download]

        $offset = 0;
        while (read(DATA, $data, BLOCKLEN, $offset)) {
                my $blockhdr = unpack "H*", substr($data, 0, BLOCKHDR)
+;
                my $blockdt  = unpack "H*", substr($data, BLOCKHDR, BL
+OCKDATA);
                my $cdrdata  = unpack "H*", substr($data, BLOCKHDR+BLO
+CKDATA, CDRLENGTH);
...
                        $offset += BLOCKLEN;
...
                        $offset += BLOCKLEN;
                        $offset -= 286;

[download]

$offset is the position in $data where the data is copied from the file but you are not capturing the actual number of bytes read and just assuming that it is always BLOCKLEN number of bytes.   So each time through the loop you are appending records to the end of $data but you are always reading from the beginning of $data. 

                my $total_record = hextoint(reverse_str(substr($blockd
+t,4)));

[download]

What does reverse_str do that reverse cannot do?   What does hextoint do that unpack or hex cannot do?

In reply to Re: How to read number of block in binary files? by jwkrahn
in thread How to read number of block in binary files? by bh_perl

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