Thanks for reply. Stories of bit is a little bit hard for me. Please point out if I am saying something wrong.

How/what?

I was wrong. I was confused with little endian and big endian. Here OP expects it's input bit array as Big Endian(N) and descending bit order(B). 

printf "0x%x\n",                #hex
    unpack("N",                 #unpack it as 32bit int ,big endian
        pack("B32",             #pack it as MSB descending bit, 32bit inte
            sprintf("%032s",    #32 length bit string
                join('',
                    @rand1))));
So, left pad works fine, even if it was an array of 16bit. 
my $num;
$num=pack('n',7); #16bit short Big endian, it's value is 7
printf "big endian, descending bit order:%s\n", unpack('B16',$num);
printf "big endian, ascending  bit order:%s\n", unpack('b16',$num);
printf "unsigned short=%d\n",unpack('n',pack('B16', unpack('B16', $num)));

printf "right pad:%s\n", unpack('B16',$num) . '0' x 16;
printf "32bit right pad=%d\n",unpack('N',pack('B32', unpack('B16',$num) . '0' x 16));
#==> this prints "32bit right pad=458752"
printf "left  pad:%s\n", '0' x 16 . unpack('B16',$num);
printf "32bit left  pad=%d\n",unpack('N',pack('B32', sprintf('%032d', unpack('B16',$num)))
#==> this prints "32bit left  pad=7"
You are the same anonymous with this. 
print  '0x'. unpack 'H*', pack("B32", substr("0" x 32 . join('',@rand1), -32));
So, you are going to say: If you need it's hexadecimal values, there is no need for decimal( unpack 'N') -> hexadecimal conversion( printf %x), just print it as hex( unpack 'H').

I am going to see your links. Thanks for reply.

In reply to Re^4: array of binaries to hex conversion by remiah
in thread array of binaries to hex conversion by bebe

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