How to get the endianness type in PHP?

Question

In C# I can get the endianness type by this code snippet:

if(BitConverter.IsLittleEndian)
{
   // little-endian is used   
}
else
{
   // big-endian is used
}

How can I do the same in PHP?

Sinuation

Detect the endianness of what specifically? – Lawabiding

For example when using socket_send($socket, $data, $len). Which endianness is used? – Sinuation

$data is an 8-bit binary string, a char sequence (like all php strings). It has no endianness. If you need to prepare binary data in a specific endianness, use the pack() and unpack() functions. – Wrennie

If you want to get the current machine endian order, you can use pack() with the format option l or L and a constant input and evaluate the result. – Bump

Answer 1

PHP's string type is an 8-bit binary string, a char sequence. It has no endianness. Thus for the most part endianness is a non-issue in PHP.

If you need to prepare binary data in a specific endianness, use the pack() and unpack() functions.

If you need to determine the machine's native endianness, you can use pack() and unpack() in the same way.

function isLittleEndian() {
    $testint = 0x00FF;
    $p = pack('S', $testint);
    return $testint===current(unpack('v', $p));
}

Wrennie

Thanks for your answer. So, where can I find a machine which returns false? :-) – Sinuation

A PowerPC should return false. If you never run on bigendian machines, why ask the question? – Wrennie

Because I don't know exaclty what machines my clients are using. – Sinuation

Answer 2

function isLittleEndian() {
    return unpack('S',"\x01\x00")[1] === 1;
}

Little-endian systems store the least significant byte in the smallest (left-most) address. Thus the value 1, packed as a "short" (2-byte integer) should have its value stored in the left byte, whereas a big-endian system would store it in the right byte.

Gawain