How do I split a large number into 8 bit numbers?

[iNerd]

If I have a large number like (new Date().getTime()), how do I seperate it into an array of byte-sized numbers, each number the next eight bits of the big number?

[David Harrison]

This should work but I haven't tested it:

var big_number=(new Date().getTime())+"";

var num_array=new Array();

for(var n=0;n<big_number.length;n++){

num_array[n]=big_number.substring(n,(n+1));

}

[iNerd]

narg! That splits the number into base-ten digits.
I need to split it into every 8 bits
Example, with binary:
bigNumber= 1111011100101011010110011111001000111111
every8bits= [11110111,00101011,01011001,11110010,00111111]

It would be something with left and right bit-shift operators (<< and >>):
0x996A<<24>>24==0x6A
0x997F<<24>>24==0x7F
0x9980<<24>>24==-0x80
0x99FF<<24>>24==-1
:confused:

[David Harrison]

var big_number=(new Date().getTime())+"";

var num_array=new Array();

var n=0;
var o=0;

while(n<big_number.length;){

n+=8;
o++;

num_array[o]=big_number.substring(n,(n+8));

}

var bin_big_number=num_array.join(",")

If you can convert big_number into binary, then this script will assign a variable (bin_big_number) a binary number in the form:

11110111,00101011,01011001,11110010,00111111

[Charles]

<script type="text/javascript">
<!--
String.prototype.reverse = function () {return this.split('').reverse().join('')}

Number.prototype.toBytes = function () {return this.toString(2).reverse().match(/\d{8}/g).join(',').reverse()}

alert (new Date().getTime().toBytes())
// -->
</script>

[iNerd]

Well, I was expecting something like using bit-shift, but I found out that JavaScript bit-shift operands don't work with more than 31 bits (at least on my platform) :mad: ....
Using mod (%) to take the last 31 bits, I can demonstrate what I was trying to work with:
z=new Date.getTime()%0x80000000;n=[(z>>>24),(z>>>16<<24>>>24),(z>>>8<<24>>>24),(z<<24>>>24)];alert(n.toString());
Something on that grounds should work but I guess the JavaScript bit-shift operands expect a signed 32 bit integer :rolleyes: ....
Oh whell, thanks anyway, I'll leave it open for a little while incase anyone else has any suggestions. I was trying to make it finite, in as few steps as possible, but if I want to use more than 31 bits than I'll have to use your method. Good job anyway.
Thanks again, iNerd.

[Jeff Mott]

I was expecting something like using bit-shiftWhat you describe would have looked something like thisvar n = new Date().getTime();
var a = new Array();
while (n) {
a.push(n & 255);
n >>= 8;
}...but as the discovered on your own, the number you're working with is too big. Charles' method is really the best way to go.

[iNerd]

Ya, that's pretty good :). Here's what I came up with while I was waiting for a reply:
t=new Date().getTime();
z=t%0x80000000;
y=(t-z)/0x80000000;
n=[y>>>1, (y<<31>>>31)|(z>>>24), z>>>16<<24>>>24, z>>>8<<24>>>24, z<<24>>>24];
The point is so that I can display large numbers (including the clock, pseudo-random, and user-entered) as string, for an interactive lesson on how different concepts of computing work:
t=new Date().getTime();
z=t%0x80000000;
y=(t-z)/0x80000000;
n=[y>>>1, (y<<31>>>31)|(z>>>24), z>>>16<<24>>>24, z>>>8<<24>>>24, z<<24>>>24];
s=String.fromCharCode(n[0], n[1], n[2], n[3], n[4]);
The tutorial will also explain how things like pseudo-random number generators work, and display things at each level (binary, hex, string; machine language, assembly, high-level).
It will include a converter to display equivilant string, alphanumeric (because it looks cool), hex, decimal, octal, and binary. What I came up with looks like this:
i=new Date().getTime();//getNumber();
z=i%0x80000000;
y=(i-z)/0x80000000;
n=[y>>>1, (y<<31>>>31)|(z>>>24), z>>>16<<24>>>24, z>>>8<<24>>>24, z<<24>>>24];
s=String.fromCharCode(n[0], n[1], n[2], n[3], n[4]);
a=i.toString(36);
h=i.toString(16).toUpperCase();
d=i.toString();
o=i.toString(8);
b=i.toString(2);
while(b.length%8) b="0"+b;
except i (for input) actually = the result of the function getNumber() which gets a number from the user.
Your methods are good, though, and I'll probably improve mine a bit using your advice (just to pro-up the code) ;).

Thanks again, iNerd

[Charles]

Please forgive us if our humble efforts weren't up to your professional standards.

[iNerd]

:confused: I said that I would improve my code with your examples, that I would pro-up my own code by using yours.

:rolleyes: Sorry, I guess I wasn't clear enough.

Bye, iNerd

[Charles]

Forgive me. It seems that I did misread your post.