String to byte/binary arrays in PHP

Let's say that you want to convert $stringA="Hello" to binary.

First take the first character with ord() function. This will give you the ASCII value of the character which is decimal. In this case it is 72.

Now convert it to binary with the dec2bin() function. Then take the next function. You can find how these functions work at http://www.php.net.

OR use this piece of code:

<?php
    // Call the function like this: asc2bin("text to convert");
    function asc2bin($string)
    {
        $result = '';
        $len = strlen($string);
        for ($i = 0; $i < $len; $i++)
        {
            $result .= sprintf("%08b", ord($string{$i}));
        }
        return $result;
    }

    // If you want to test it remove the comments
    //$test=asc2bin("Hello world");
    //echo "Hello world ascii2bin conversion =".$test."<br/>";
    //call the function like this: bin2ascii($variableWhoHoldsTheBinary)
    function bin2ascii($bin)
    {
        $result = '';
        $len = strlen($bin);
        for ($i = 0; $i < $len; $i += 8)
        {
            $result .= chr(bindec(substr($bin, $i, 8)));
        }
        return $result;
    }
    // If you want to test it remove the comments
    //$backAgain=bin2ascii($test);
    //echo "Back again with bin2ascii() =".$backAgain;
?>

If you're trying to access a specific part of a string you can treat it like an array as-is.

$foo = 'bar';
echo $foo[0];

output: b

There is no such thing as a binary array in PHP. All functions requiring byte streams operate on strings. What is it exactly that you want to do?