unexpected result in php output with larger strings - php

Question

I am trying to create a binary/hexadecimal converter to convert a denary(base 10) number/value into binary and hexadecimal.
It works fine so far for binary until the input from the form is greater than 11 digits and over(string length), ruffly as it seems to variety. after 11 digits it starts adding " - " into the outcome. Im not sure were this is coming from as I don't have an " - " in the code.
I wasn't sure if this was something to do with large integers as I saw some other questions on that topic(not in php however it was java, so not sure if there is something simpler in php)
That said I was under the impression that form inputs were always strings.
To test if a variable is a number or a numeric string (such as form input, which is always a string), you must use is_numeric(). - from : http://www.php.net/manual/en/function.is-float.php
(haven't yet got to hexadecimal but needed to mention it as some of the following code contains parts for it.)
here is the php code (note: I do check user input just not added it yet)
$inpu = $_POST['number'];
$numinput = $_POST['number'];
if (is_numeric($numinput))
{
while ($numinput >= 1)
{
$binary .= $numinput % 2;
$numinput = $numinput / 2;
}
$mult = strlen($binary) % 4;
echo gettype($numinput) . "<br />";
echo gettype($binary) . "<br />";
echo gettype($mult) . "<br />";
echo $mult . "<br />";
while ($mult < 4)
{
$binary.= "0";
$mult++;
}
$revbinary = strrev($binary);
echo $inpu . " in binary = " . $revbinary ;
echo "<br /> <br />";
echo chunk_split($revbinary, 4);
echo "<br />" . gettype($revbinary) . "<br />";
echo gettype($inpu) . "<br />";
}
else
{
if (is_numeric($numinput))
{
echo "$numinput is over the max value of 255";
}
else
{
echo "your entry is not a vaild number <br />";
echo $numinput;
}
}
Im not looking for completed version of this code as you would ruin my fun, I am just wondering why there is a "-" being entered after 11 digits or so. It also did't add the symbol before I added :
$mult = strlen($binary) % 4;
echo $mult . "<br />";
while ($mult < 4)
{
$binary.= "0";
$mult++;
}
This was to split the binary into 4s ( 0011 1101 0010 0110 ).
Edit: wondered if this would be useful:
echo gettype($numinput); result double
echo gettype($binary); result string
echo gettype($mult); result integer
gettype($revbinary); result string
echo gettype($inpu); result string
still trying to work this out myself.
Any advice is much appreciated Thanks

Answer 1

I would suggest simply using decbin() and dechex(). Those are functions included in php, which do exactly what you're trying to accomplish.
You might want to check if it is a number first (like you are already doing).
Then cast it to an integer (through intval()) and then apply decbin() and dechex()
http://php.net/manual/de/function.decbin.php
http://www.php.net/manual/de/function.dechex.php
http://php.net/manual/de/function.intval.php