How to deal with binary data in php (not binary string)?

Question

I wrote a C++ program which send POST data to php. My data is 123456 in binary, which is 0x0001e240.

My php file reads like

$f=fopen("php://input", "r");
if (!$f) die ("cannot open");
$data = fread($f, 4);
echo $data;

In my receiving program (in C++), I can see the echoed data is exactly 0x0001e240, so I believe php did accept a pure binary thing and saved into $data.

However, I want to get 123456 in php. I tried functions like bindec, hexdec, and so on but none of them works. How can I get the number from $data.

Also, do I need to care about endians in php? I am working locally now with windows environment but I will finally put my codes onto cloud.

Edit

$f=fopen("test.bin", "rb");
if (!$f) die ("cannot open");
$data = fread($f, 4);
echo $data;

where test.bin is a bin file which contains 0x0001e240. It seems that I got a string in $data which is composited with ASCII of 0x00, 0x01, 0xe2, and 0x40. How can I make them into a number value?

Ry- · Accepted Answer · 2013-07-09 19:26:21Z

1

You can use unpack:

$num = unpack('n', $data);

Use an uppercase letter for an unsigned integer, and a v (or V) for little-endian. Yes, you have to worry about endianness. Just find out what it is and stick with it.

answered Jul 9, 2013 at 19:26

Ry-♦

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2 Comments

科张 Over a year ago

Thanks for your reply. But I got a notice saying "Notice: Array to string conversion" and I didn't get the number I want.

科张 Over a year ago

Oops I knew what I was wrong. and I should use N for 32bit. I think that works! thanks a lot!

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