Question

here is the skinny (scroll down to see the problem): I am doing Huffman Encoding to compress a file using PHP (for a project). I have made the map, and made everything into a string like so:

00101010001100001110011101001101111011111011

Now, I need to convert that into an actual binary string, in its current state, it is only a string of 1s and 0s.

Here is the problem:

The string of 1s and 0s is 17,747,595 characters long, and it is really slowing down at around 550,000

This is the code I have:

<?php

$i=0
$len = strlen($binaryString);

while ($i < $len){
    $section = substr($binaryString,$i,$i+8);
    $out .= chr(bindec($section));
    $i=$i+8;
}

?>

How can I make this efficient enough to run the 17 million character string?

Thanks very much for any support!

Answer 1

You don’t need to loop you can use gmp with pack

$file = "binary.txt";
$string = file_get_contents($file);
$start = microtime(true);

// Convert the string
$string = simpleConvert($string);
//echo $string ;

var_dump(number_format(filesize($file),2),microtime(true)- $start);

function simpleConvert($string) {
    return pack('H*',gmp_strval(gmp_init($string, 2), 16));
}

Output

string '25,648,639.00' (length=13) <---- Length Grater than 17,747,595
float 1.0633520126343  <---------------- Total Conversion Time 

Links

• Original Dictionary File (349,900 words) 3,131KB
• Binary Version 25,048 KB

Note Solution requires GMP Functions