Question

I have a string for example: “10001000101010001” in PHP
I am compressing it with gzcompress, but it compresses ASCII equivalent.
I would like to compress the string as if it were binary data not it ASCII binary equivalent.

Bascially I have 2 problems:

1. how to convert a list of 1s and 0s into binary
2. compress the resulting binary with gzcompress

thanks in advance.

Answer 1

Take a look at the bindec() function.

Basically you’ll want something like (dry-coded, please test it yourself before blindly trusting it)

function binaryStringToBytes($binaryString) {
    $output = '';
    for($i = 0; $i < strlen($binaryString); $i += 8) {
        $output .= chr(bindec(substr($binaryString, $i, 8)));
    }
    return $output;
}

to turn a string of the format you specified into a byte string, after which you can gzcompress() it at will.

The complementary function is something like

function bytesToBinaryString($byteString) {
    $out = '';
    for($i = 0; $i < strlen($byteString); $i++) {
        $out .= str_pad(decbin(ord($byteString[$i])), 8, '0', STR_PAD_LEFT);
    }
    return $out;
}