Converting string of 1s and 0s into binary value, then compress afterwards ,PHP

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:

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

thanks in advance.

Maybe you could write your "binary" string into a file and call gzfile(). — ComFreek
– ComFreek, Commented Jul 10, 2011 at 15:06

Community · Accepted Answer · 2023-11-17 19:41:46Z

3

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;
}

edited Nov 17, 2023 at 19:41

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answered Jul 10, 2011 at 15:10

AKX

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2 Comments

chineerat Over a year ago

Hi @AKX! thanks for your help. So therefore can I do this? $output = ''; for($i = 0; $i < strlen($string_to_compress); $i += 8) { $output .= chr(bindec(substr($string_to_compress, $i, 8))); } gzcompress($bin_output_comp, 7);

AKX Over a year ago

You could just use those functions as-is in your source and then simply do $compressed = gzcompress(binaryStringToBytes('10001000101010001'), 7);.

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