Building a binary 'string' with PHP

[CptDondo]

I am working with a communications protocol that requires me to pack an
array of integers into a binary 'string'.

Let's say I have this:

int[0] = 0x1234
int[2] = 0x5678
int[3] = 0x9abc
int[4] = 0xdef0

I have to produce a string containing

0x 12 34 56 78 9a bc de f0

and send it off. The string contains the ints packed together in
big-endian order: HI LO HI LO HI LO.

In C, I can do this pretty easily, but I am not familiar enough with
PHP's data handling. I don't even know where to begin.

I know PHP can do it, since it handles images but how do you build
something like this from scratch? How can you build a string byte by byte?

--Yan

[petersprc]

Re: Building a binary 'string' with PHP

Try pack('n*', 0x1234, 0x5678, 0x9abc, 0xdef0)

CptDondo wrote:

I am working with a communications protocol that requires me to pack an
array of integers into a binary 'string'.
>
Let's say I have this:
>
int[0] = 0x1234
int[2] = 0x5678
int[3] = 0x9abc
int[4] = 0xdef0
>
I have to produce a string containing
>
0x 12 34 56 78 9a bc de f0
>
and send it off. The string contains the ints packed together in
big-endian order: HI LO HI LO HI LO.
>
In C, I can do this pretty easily, but I am not familiar enough with
PHP's data handling. I don't even know where to begin.
>
I know PHP can do it, since it handles images but how do you build
something like this from scratch? How can you build a string byte by byte?
>
--Yan