String to byte array in php

Question

How can I get the byte array from some string which can contain numbers, letters and so on? If you are familiar with Java, I am looking for the same functionality of the getBytes() method.

I tried a snippet like this one:

for($i = 0; $i < strlen($msg); $i++){
    $data.=ord($msg[$i]);
        //or $data[]=ord($msg[$1]); 
}

but without success, so any kind of help will be appreciated.

PS: Why do I need this at all!? Well, I need to send a byte array via fputs() to a server written in Java...

Answer 1

@Sparr is right, but I guess you expected byte array like byte[] in C#. It's the same solution as Sparr did but instead of HEX you expected int presentation (range from 0 to 255) of each char. You can do as follows:

$byte_array = unpack('C*', 'The quick fox jumped over the lazy brown dog');
var_dump($byte_array);  // $byte_array should be int[] which can be converted
                        // to byte[] in C# since values are range of 0 - 255

By using var_dump you can see that elements are int (not string).

   array(44) {  [1]=>  int(84)  [2]=>  int(104) [3]=>  int(101) [4]=>  int(32)
[5]=> int(113)  [6]=>  int(117) [7]=>  int(105) [8]=>  int(99)  [9]=>  int(107)
[10]=> int(32)  [11]=> int(102) [12]=> int(111) [13]=> int(120) [14]=> int(32)
[15]=> int(106) [16]=> int(117) [17]=> int(109) [18]=> int(112) [19]=> int(101)
[20]=> int(100) [21]=> int(32)  [22]=> int(111) [23]=> int(118) [24]=> int(101)
[25]=> int(114) [26]=> int(32)  [27]=> int(116) [28]=> int(104) [29]=> int(101)
[30]=> int(32)  [31]=> int(108) [32]=> int(97)  [33]=> int(122) [34]=> int(121)
[35]=> int(32)  [36]=> int(98)  [37]=> int(114) [38]=> int(111) [39]=> int(119)
[40]=> int(110) [41]=> int(32)  [42]=> int(100) [43]=> int(111) [44]=> int(103) }

Be careful: the output array is of 1-based index (as it was pointed out in the comment)

Answer 2

print_r(unpack("H*","The quick fox jumped over the lazy brown dog"))

Array ( [1] => 54686520717569636b20666f78206a756d706564206f76657220746865206c617a792062726f776e20646f67 ) 

T = 0x54, h = 0x68, ...

You can split the result into two-hex-character chunks if necessary.

Answer 3

PHP has no explicit byte type, but its string is already the equivalent of Java's byte array. You can safely write fputs($connection, "The quick brown fox …"). The only thing you must be aware of is character encoding, they must be the same on both sides. Use mb_convert_encoding() when in doubt.

Answer 4

You could try this:

$in_str = 'this is a test';
$hex_ary = array();
foreach (str_split($in_str) as $chr) {
    $hex_ary[] = sprintf("%02X", ord($chr));
}
echo implode(' ',$hex_ary);

Answer 5

In PHP, strings are bytestreams. What exactly are you trying to do?

Re: edit

Ps. Why do I need this at all!? Well I need to send via fputs() bytearray to server written in java...

fputs takes a string as argument. Most likely, you just need to pass your string to it. On the Java side of things, you should decode the data in whatever encoding, you're using in php (the default is iso-8859-1).

Answer 6

I found several functions defined in http://tw1.php.net/unpack are very useful.
They can covert string to byte array and vice versa.

Take byteStr2byteArray() as an example:

<?php
function byteStr2byteArray($s) {
    return array_slice(unpack("C*", "\0".$s), 1);
}

$msg = "abcdefghijk";
$byte_array = byteStr2byteArray($msg);

for($i=0;$i<count($byte_array);$i++)
{
   printf("0x%02x ", $byte_array[$i]);
}
?>