Display full 1-128 bit decimal to binary using PHP

Question

I know this seams to be easy but, I have a question to this particular situation. I already know how to convert decimal to binary using PHP, but I want to display the full bit sequence, but surprisingly, I don't know how.

the conversion must be like this:

converting 127(decimal) to binary using PHP = 1111111. the bit sequence is 1-128 for every 
octet(IP Address) so this must output = 01111111 even 128 is not used.
2nd Example:
1(decimal) to binary = 01. Want to display the full 1-128 binary sequence even if
128,64,32,16,8,4,2 is not used it must be like this 00000001 not 01.

this is my PHP code:

<?php

        $octet1 = $_POST["oct1"];
        $octet2 = $_POST["oct2"];
        $octet3 = $_POST["oct3"];
        $octet4 = $_POST["oct4"];
        echo decbin($octet1) ," ", decbin($octet2) ," ", decbin($octet3) ," ", decbin($octet4);

    ?>

this only displays the shortened binary just like this:

16 to binary is 10000 or but i want to display this 00010000(Full length)

How can I do that?

Answer 1

How about using sprintf with b format specifier:

echo sprintf("%08b", 127);
// 01111111
echo sprintf("%08b.%08b.%08b.%08b", 127, 0, 0, 1);
// 01111111.00000000.00000000.00000001

Answer 2

You need to pad it:

echo str_pad($str, 8, '0', STR_PAD_LEFT);