Get total value of individual ones in a binary string

PHP
1

I’m creating a cryptographically secure random string generator based on openssl_random_pseudo_bytes.

When the binary string is created, how do I get the binary representation like this 0011011011100101 and add the ones up.

So 0011011011100101 would convert to 9.

2

simple way would be to perform str_replace and remove the 0’s then check the length of the string

3 
<?php 
function generate_secure_token($length = 16) {
	/* important! this has to be a crytographically secure random generator */	
	return bin2hex(openssl_random_pseudo_bytes($length));            
}

Ooops…didn’t read the whole thing…

4

Alternatively:

$str = '0011011011100101';
$num = array_sum(str_split($str));
5 
$str = '00101101010101100101101001110101010';
$cnt = strlen(preg_replace("/0/", "", $str));

Of course for performance:

$str = '00101101010101100101101001110101010';
$cnt = strlen(str_replace("0", "", $str));

Edit: just as @cpradio said :smile:

Or:

$count = 0;
$str = '00101101010101100101101001110101010';
$replaced = str_replace("1", "", $str, $count);
// $count now has your sum

Or:

$str = '00101101010101100101101001110101010';
$statement = '$count = ' . preg_replace("/(\d)/", "$1+", $str) . '0;';
eval($statement);
// $count now has your sum
6

Maybe I’m missing something but…

substr_count($binaryString, '1');

???

1 Like
7

Thanks all but…

When you get raw output how do you get the string as zeros and ones? Sorry, I probably didn’t question it very clearly. Unless I’m missing something when you call openssl_random_pseudo_bytes you don’t get it in juman readable zeros and ones. I guess that is the question. :smile:

Thanks.

8

Found the answer: http://php.net/manual/en/function.base-convert.php

9

Ah, that explains the confusion. Going by your first example it looked like your wanted to get the number of positive bits not the equivalent value.

Glad you solved it :thumbsup:

10

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